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Across

1 A plant pigment that absorbs sunlight. (11)

4 The links between the energy that carnivores get from eating to the energy captured by photosynthesis. (4,5)

7 Chlorophyll absorbs every color of sunlight except this. (5)

8 A compound needed for photosynthesis. (6,7)

10 The product of photosynthesis. (5)


Down

2 The process by which plants and some bacteria use the energy from sunlight to produce sugar. (14)

3 Part of the plant where photosynthesis generally occurs. (6)

5 A compound needed for photosynthesis. (5)

6 An animal that eats plants. (9)

9 A by-product of photosynthesis. (6)

10 Number of molecules of oxygen produced along with one molecule of sugar. (3)


CHAPTER 7 – CONTROL & COORDINATION
KEY CONCEPTS & GIST OF THE LESSON


  • Coordination-The working together of various organs of the body of an organism in a proper manner to produce appropriate reaction to a stimulus is called coordination.




  • Stimulus- The changes in the environment to which an organism responds and reacts is called Stimulus




  • Control & coordination in animals- takes place by (i) Nervous system & (ii) Endocrine system




  • Nervous system

Stimulus → Receptor organ → Sensory nerve → Brain/Spinal cord

Response ← Effector organ ← Motor nerve




  • Endocrine system

Stimulus → Endocrine organ → Secrete hormone → Hormone in blood

Response ← Target organ



  • Parts of the Nervous system – (i) Brain (ii) Spinal cord (iii) Nerves (Neurons)




  • A Neuron is the structural & functional unit of Nervous system




  • Parts of a neuron- (i) Dendrites (ii) Cell body (iii) Axon




  • Synapse- Space/junction between two adjacent nerves is called Synapse.




  • Passing of information takes place –(i) By Electric impulse (inside the neuron) and (ii) In the form of chemicals (At synapse)




  • Reflex action- Spontaneous, involuntary and automatic response to a stimulus to protect us from harmful situations. Eg. On touching a hot object unknowingly we instantly withdraw our hand.




  • Reflex arc- The pathway of the reflex action is called Reflex arc.

Stimulus → Receptor organ → Sensory nerve → Spinal cord →→Effector organ→ Response

Refer to figure 7.2 page no. 117 of N.C.E.R.T Text book)




  • Nervous system- (1) Central Nervous system (CNS) (2) Peripheral Nervous system (PNS)

(i) Brain (i) Autonomic Nervous system

(ii) Spinal cord (ii) Voluntary Nervous system




  • Brain (i) Centre of coordination of all activities (ii) Thinking is involved (iii) Complex process

  • Parts of brain- Refer to figure 7.3 page no. 118 of N.C.E.R.T Text book




Fore brain

Mid brain

Hind brain

(i) Cerebrum

(ii) Thalamus (iii) Hypothallamus


----------



(i) Cerebellum (ii) Pons (iii) Medulla oblongata




  • Fore brain

Cerebrum- (i) Main thinking and largest part of the brain.

(ii) It has 3 main areas-



          1. Sensory area- to receive impulses from sense organs via Receptors

          2. Motor area- control voluntary movements.

          3. Association areas- Reasoning, learning & intelligence.

Thalamus – It relays sensory information to the Cerebrum

Hypothallamus- It forms the link between Nervous system & Endocrine system




  • Mid brain- It connects Fore brain and Hind brain. Controls reflex of eyes & ears




  • Hind brain- Connects the Fore brain & Hind brain

Cerebellum – Controls & coordinates muscular movements, maintaining body posture and equilibrium.

Pons- Acts as a bridge between brain & spinal cord

Medulla oblongata- Controls involuntary actions like blood pressure, salivation, vomiting, etc.


  • Spinal cord- Cylindrical or tubular structure extending downwards from the Medulla oblongata.




  • Protection of the brain & the spinal cord- (i) Bony outer covering: skull for the brain & vertebral column for the spinal cord.

(ii) Cerebrospinal fluid present in between the three membranes.


  • Action caused by Nervous tissue Information → Nervous tissue → Brain Muscles → Causes action

  • Path or action- Nerve impulse → Muscle cell → Changes shape due to special proteins

Action caused ← Shorter form of muscles ← Change shape & arrangement of cell



  • Chemical communication by hormones- (advantages)

    1. Electrical impulses have their limitations because they reach only those cells connected to the nervous tissue.

    2. Also the nerve cells cannot generate & transmit impulses continuously.

    3. Electrical communication is slower.




(ii) Are secreted in small amounts & may act in nearby places or distant places.

  1. Do not take part in the reaction & are destroyed immediately.


  • Hormones are secreted by- Endocrine glands & Exocrine glands



S. No.

Endocrine glands

Exocrine glands

1.

Ducts absent

Ducts present

2.

Secrete hormones

Secrete enzymes

3.

Secreted in blood

Secreted in ducts of glands

4.

Situated away from the site of action

Situated near the site of action



  • Some glands which act as both endocrine & exocrine



Gland

Endocrine function

Exocrine function

Pancreas

Produces insulin & Glucagon hormone.

Produces digestive enzyme. (pancreatic amylase)

Testes

Produces hormone Testosterone

Produces male gametes (reproductive cells)

Ovaries

Produces hormone Oestrogen

Produces female gametes (reproductive cells)




Refer to figure 7.7 page no. 124 of N.C.E.R.T Text book)


Endocrine gland

Hormone

Function

Pituitary gland

Growth hormone

Body growth, development of bones & muscles

(If excess- Gigantism)

(If less- Dwarfism)


Thyroid gland

Thyroxine

Regulates carbohydrate, protein & fat metabolism( If less- Goitre_

Pancreas

Produces insulin & Glucagon hormone

Regulates blood sugar levels (if less diabetes is caused)

Testes in males

Produces hormone Testosterone

Development of secondary male characters like deep voice, beard, etc.

Ovaries in females

Produces hormone Oestrogen

Development of secondary female characters like mammary glands, menstrual cycle, maintenance of pregnancy.

  • Coordination in plants- Only chemical coordination is present in plants.

  • Tropic movements- The movements of plants in the direction of stimulus (positive) or away from it (negative) are called tropic movements. E.g. Phototropism, Geotropism. Chemotropism.

Refer to figure 7.4 & 7.5 page no. 121 of N.C.E.R.T Text book)

  • Nastic movements -The movements of plants independent of stimuli are called nastic movements. E.g.- Touch me not plant leaves close when touched.

  • Plant hormones (Phytohormones)

Examples- 1. Auxins- Help in growth of root & shoot tips.

2. Gibberellins- Help in vegetative growth

3. Cytokinins- Promote cell division

4. Abscissic acid - Inhibits growth & causes wilting (falling) of leaves



  • Important diagrams-

    1. Structure of neuron (nerve cell)2.Reflex arc 3.Human brain4.Endocrine glands .

  • Important activities-

  1. To compare taste of sugar and food with open & blocked nostrils.

  2. To demonstrate the response of a plant to the direction of light.

  3. To demonstrate hydrotropism.

MIND MAP

CONTROL AND CO-ORDINATION


ANIMALSSSSDSS

NERVOUS SYSTEM

ENDOCRINE SYSTEM

REFLEX ACTION


CNS


PNS


Hormone secreted by glands

Reflex arc

Brain, spinal cord

Neuron

Sensory

Motor

PLANTS

Plant movement

Tropic

Nastic

Hormones

Growth promoting

Growth inhibiting

Independent of stimulus

Direction of stimulus



CONTROL AND CO - ORDINATION

FORMATIVE ASSESSMENT I

Q. PAPER
MARKS-30 TIME- 70 MINUTES
Instructions:

  • Questions : 1 to 5 – 1 Mark each

  • Questions : 6 to 9 – 2 Marks each

  • Questions : 10 to 13 – 3 Marks each

  • Question 14 – 5 Marks

  1. Which endocrine gland is unpaired?

  2. Which part of the brain controlled posture and balance of the body?

  3. Where in a neuron, conversions of electrical signal to a chemical signal occur?

  4. Which gland secretes digestive enzyme as well as hormones?

  5. We suddenly withdraw our hand when a pin pricks. Name the type of response involved in this action.

  6. What is a tropic movement? Explain with an example.

  7. What will happen if intake of iodine in our diet is low?

  8. Draw the structure of neuron and label the following on it:

    1. Nucleus

    2. Dendrite

    3. Cell body

    4. Axon

  9. Why are some patients of diabetes treated by giving injections of insulin?

  10. Why is the flow of signals in a synapse from axonal end of one neuron but not the reverse?

  11. What are reflex actions? Explain reflex arc.

  12. What are the major parts of the brains? Mention the functions of each.

  13. How does chemical co – ordination take place in animals?



    1. Name the various plant hormones.

    2. Give physiological effects of hormones on plant growth and development.


HOTS QUESTIONS (SOLVED / UNSOLVED)


Q1. Which hormone:

1. prepares the body for action?

2. controls the amount of sugar (glucose) in blood?

3. brings about changes in boys at puberty?

4. brings about changes in girls at puberty?

Ans. a) Adrenaline b) Insulin

c) Testosterone d) Oestrogen

Q2. i) Name the hormone produced by thyroid gland.

ii Which mineral is necessary for the synthesis of the above hormone?

iii Name the disease suffer from the deficiency of this mineral.

iv Write the function of the above hormones?

Q3. What is chemotropism? Give one example of chemotropism.





ORAL QUESTIONS



What is the basic unit of nervous system?



How do neuron conduct message from brain to other parts?



What do you mean by CNS?



What are its main parts?



Which part controls reflex action?



What are endocrine glands?



What is the secretion of endocrine gland called?



Name a gland of human body which secretes both enzymes and hormone.



Which plant hormone helps in cell division?



Which hormones help on stem elongation?







QUIZ



Which system of our body is made of organised network for conducting information in the body?



Which part of the neuron receives information?



What is the name of the neuron which remains between the sensory neuron and the motor neuron? Where is it located?



Which part of the brain helps us to do activities like riding a cycle and walking in a straight line?



What are two major types of muscles we have?



What causes change in leave of ‘touch me not’ plant?



Which hormone helps us to prepare to combat adverse condition?



Name a female sex organ which produces gametes as well as female hormone.



Cross word puzzle: Nervous system

Clues

ACROSS

1. Composed of the brain and spinal cord (3 words).

8. Contains photoreceptors; on the inner posterior portion of eye.

9. "Inside the mouth"

11. Electrical brain activity recorded with scalp or brain electrodes

(abbreviation).

13. Necessary for hearin

17. Neurotransmitter in brain, spinal cord and peripheral nervous system

(abbreviation).

18. Outermost layer of meninges.

19. Neurotransmitter lacking in patients with Parkinson's disease.

21. Supportive cells of the nervous system; "glue".

22. Nerve cell.

23. Photoreceptor that is not used for color vision.

24. Photoreceptor that is used for color vision.

26. The sense of hearing.

29. Opposite of "Yes"

30. Junction between two neurons.


DOWN

1. In the brain, it is the outermost layer of the gray matter.

2. The fifth cranial nerve.

3. The middle layer of the meninges.

4. The part of the cell containing chromosomes.

5. Period of sleep when dreams occur (abbreviation).

6. The second cranial nerve.

7. Fat-like substance that surrounds some axons.

10. The first cranial nerve.

12. Fluid that fills the ventricles (abbreviation).

14. Part of neuron that takes information TO the cell body.

16. Short for "mother".

18. Electrical brain activity between 2 and 4 Hz.

20. Part of neuron that takes information AWAY from the cell body.

22. A short written letter.

24. Abbreviation for 1 across.

25. Organ for vision.

27. Opposite of "off".



28. Opposite of "yes".

ANSWERS: Cross word puzzle: Nervous system


ELECTRICITY

GIST OF THE LESSON

  1. Positive and negative charges: The charge acquired by a glass rod when rubbed with silk is called positive charge and the charge acquired by an ebonite rod when rubbed with wool is called negative charge.

  2. Coulomb: It is the S.I. unit of charge. One coulomb is defined as that amount of charge which repels an equal and similar charge with a force of 9 x 109 N when placed in vacuum at a distance of 1 meter from it. Charge on an electron = -1.6 x 10-19 coulomb.

  3. Static and current electricities: Static electricity deals with the electric charges at rest while the current electricity deals with the electric charges in motion.

  4. Conductor: A substance which allows passage of electric charges through it easily is called a ‘conductor’. A conductor offers very low resistance to the flow of current. For example copper, silver, aluminium etc.

  5. Insulator: A substance that has infinitely high resistance does not allow electric current to flow through it. It is called an ‘insulator’. For example rubber, glass, plastic, ebonite etc.

  6. Electric current: The flow of electric charges across a cross-section of a conductor constitutes an electric current. It is defined as the rate of flow of the electric charge through any section of a conductor. Electric current = Charge/Time or I = Q/t Electric current is a scalar quantity.

  7. Ampere: It is the S.I. unit of current. If one coulomb of charge flows through any section of a conductor in one second, then current through it is said to be one ampere. 1 ampere = 1 coulomb/1 second or 1 A = 1C/1s = 1Cs-1 1 milliampere = 1 mA = 10-3 A 1 microampere = 1µA = 10-6 A

  8. Electric circuit: The closed path along which electric current flows is called an ‘electric circuit’.

  9. Conventional current: Conventionally, the direction of motion of positive charges is taken as the direction of current. The direction of conventional current is opposite to that of the negatively charged electrons.

  10. Electric field: It is the region around a charged body within which its influence can be experienced.

  11. Electrostatic potential: Electrostatic potential at any point in an electric field is defined as the amount of work done in bringing a unit positive charge from infinity to that point. Its unit is volt. Positive charges move from higher to lower potential regions. Electrons, being negatively charged, move from lower to higher potential regions.

  12. Potential difference between two points: The Potential difference between two points in an electric field is the amount of work done in bringing a unit positive charge from one to another. Potential difference = Work done/Charge or V = W/Q

  13. One volt potential difference: The Potential difference between two points in an electric field is said to one volt if one joule of work has to be done in bringing a positive charge of one coulomb from one point to another. 1 volt = 1 joule/1 coulomb or 1 V = 1J/1C

  14. Galvanometer: It is device to detect current in an electric circuit.

  15. Ammeter: It is device to measure current in a circuit. It is always connected in series in a circuit.

  16. Voltmeter: It is a device to measure potential difference. It is always connected in parallel to the component across which the potential difference is to be measured.

  17. Ohm’s law: This law states that the current passing through a conductor is directly proportional to the potential difference cross its ends, provided the physical conditions like temperature, density etc. remains unchanged.

V α I or V = RI

The proportionality constant R is called resistance of conductor.



  1. Resistance: It is a property of a conductor by virtue of which it opposes the flow of current through it. It is equal to the ratio of the potential difference applied across its ends and the current flowing through it.

Resistance = Potential difference/Current or R = V/I

  1. Ohm: It is the S.I. unit of resistance. A conductor has a resistance of one ohm if a current of one ampere flows through it on applying a potential difference of one volt across its ends. 1 ohm = 1 volt/1 ampere or 1Ω = 1V/1A

  2. Factors on which resistance of a conductor depends: The resistance R of a conductor depends

i) Directly on its length L i.e. R α L. ii) inversely on its area of cross-section A i.e. R α 1/A iii) on the nature of material of the conductor on. On combining the above factors, we get R α L/A R = ρ * L/A The proportionality constant ρ is called resistivity of conductor.

  1. Resistivity: It is defined as the resistance offered by a cube of a material of side 1 m when current flows perpendicular to its opposite faces. Its S.I. unit is ohm-meter (Ωm). Resistivity, ρ = RA/L

  2. Equivalent resistance: If a single resistance can replace the combination of resistances in such a manner that the current in the circuit remains unchanged, then that single resistance is called the equivalent resistance.

  3. Laws of resistances in series: i) Current through each resistance is same. ii) Total voltage across the combination = Sum of the voltage drops. V= V1 + V2 + V3 iii) Voltage drops across any resistor is proportional to its resistance. V1 = IR1, V2 = IR2, V3 = IR3 iv) Equivalent resistance = Sum of the individual resistances. Rs = R1 + R2 + R3 v) Equivalent resistance is larger than the largest individual resistance.

  4. Laws of resistances in parallel: i) Voltage across each resistance is same and is equal to the applied voltage. ii) Total current = Sum of the currents through the individual resistances. I = I1 + I2 + I3 iii) Currents through various resistances are inversely proportional to the individual resistances. I1 = V/R1, I2 = V/R2, I3 = V/R3 iv) Reciprocal of equivalent resistance = Sum of reciprocals of individual resistances. 1/Rp = 1/R1 + 1/R2 + 1/R3 v) Equivalent resistance is less than the smallest individual resistance.

  5. Joule’s law of heating: It states that the heat produced in a conductor is directly proportional to (i) the square of the current I through it (ii) proportional to its resistances R and (iii) the time t for which current is passed. Mathematically, it can be expressed as H = I2Rt joule = I2Rt/4.18 cal or H = VIt joule = VIt/4.18cal

  6. Electric energy: It is the total work done in maintaining an electric current in an electric circuit for given time.

Electric energy, W = VIt = I2Rt joule

  1. Electrical power: Electrical power is the rate at which electric energy is consumed by an appliance.

P = W/t = VI = I2R = V2/R

  1. Watt: It is the S.I. unit of power. The power of an appliance is 1 watt if one ampere of current flows through it on applying a potential differences of 1 volt across its ends. 1 watt = 1 joule/1 second =1 volt x 1 ampere or 1 W = 1 Js-1 = 1 VA 1 kilowatt = 1000 W

  2. Kilowatt hour: It is the commercial unit of electrical energy. One kilowatt hour is the electric energy consumed by an appliance of 1000 watts when used for one hour. 1 kilowatt hour (kWh) = 3.6 x 106 J



MIND MAP


ELECTRIC POWER

p=w/t


Or VI =I2R = V2/R
Unit of Power - Watt


ELECTRIC ENERGY

Work = VIT = I 2RT

Unit of E E – Watt-Hr or Kw.Hr

1 Kwhr= 3.6 *105 J



P D = work done / charge

V = W /Q


UNIT OF V is Volts


JOULE’S LAW

H = I2RT

Or H = VIT

Unit of heat energy -Joules



ELECTRICITY

OHM’S LAW

V = IR


Unit of R - Ohms

RESISTANCE = PD/current

R = V/I




RESISTIVITY = RA / l

Unit of Resistivity – Ohm-m




RESISTANCE IN SERIES

RS = R1 + R2 + R3 …..



RESISTANCE IN PARALLEL

1/RP = 1/R1 + 1/R2 + 1/R3 …….







ELECTRICITY

FORMATIVE ASSESSMENT I

Q. PAPER

MARKS-30 TIME- 70 MINUTES



Instructions:

  • Questions : 1 to 5 – 1 Mark each

  • Questions : 6 to 9 – 2 Marks each

  • Questions : 10 to 13 – 3 Marks each

  • Question 14 – 5 Marks



Define resistivity of material.



What is the power of torch bulb rated at 2.5V and 500mA?



Why series arrangement not used for connecting domestic electrical appliances in a circuit?



Which has higher resistance – a 50W bulb or a 2.5W bulb and how many times?



What is the direction of flow of conventional current?



Why is it not advisable to handle electrical appliances with wet hands?



Two electric bulbs marked 100W 220V and 200W 200V have tungsten filament of same length. Which of the two bulbs will have thicker filament?



How does the resistance of a wire vary with its area of cross section?



Draw the following symbols




      1. Battery

      1. Switch closed




      1. Resistor of resistance R

      1. Voltmeter



A geyser is rated 1500W, 250V. This geyser is connected to 250V mains. Calculate –

      1. The current drawn

      2. The energy consumed in 50hrs.

      3. The cost of energy consumed at Rs. 2.20 per kWh.



What is the function of an electric fuse? Name the material used for making fuse. In household circuit where is fuse connected?



Write one important advantage of using alternative current. How alternating current differ from direct current?



What is the difference between short circuiting and overloading?



  1. Draw diagram showing three resistors R1, R2 and R3 in series.

  2. Two resistors of resistance 4 and 12

  1. In parallel

  2. In series

Calculate the values of effective resistance in each case.


HOTS QUESTIONS (SOLVED / UNSOLVED)

Q.1.

Why is the tungsten metal more coiled in the bulb and not installed in straight parallel wire form?

Ans.

The coiled wire of tungsten increases the surface area of the wire in very less space so as to emit more light and helps in glowing with more intensity.

Q.2.

Why are fairy decorative lights always connected in parallel?

Ans.

When the fairy lights are connected in series the resistance offered will be greater and brightness of the bulbs will be affected. But in parallel connection all the bulbs will glow with same intensity and if any more bulbs gets fused the other bulbs will continue to glow.


Q.3.

What will happen when -

  1. Voltmeter is connected in series?

  2. Ammeter is connected in parallel?

Ans.

  1. Negligible current will pass through the circuit because the voltmeter has a very high resistance.

  2. Ammeter will get damaged due to flow of large amount of current through it, because it has low resistance.

ELECTRICITY

ORAL QUESTIONS (CONVERSATION TYPE)



  1. Why is electricity more useful than other forms of energy?

  2. How is static electricity different from current electricity?

  3. What are conductors? Give examples.

  4. What are insulators? Give examples.



  1. What constitutes an electric current?

  2. Name the SI unit of electric charge.

  3. Which is bigger – c coulomb of charge or a charge of an electron?

  4. How much is the charge on an electron? Can a charge less than this value exist?

  5. What is the number of electrons constituting one coulomb of charge?



  1. Define electric current.

  2. Name the SI unit of current. Define one ampere.

  3. Is electric current a scalar of vector quantity?



  1. What does an electric circuit mean?

  2. When does the current flow in an electric circuit?

  3. How can the current be kept continuous in a conductor?

  4. Which particles constitute current in a metallic conductor?



  1. Define potential difference.

  2. Name the SI unit of potential difference.

  3. What is meant by saying that a potential difference between two points in 1volt?

  4. What is the relationship between work done, potential difference and charge moved?

ORAL QUESTIONS



Which unit is equivalent of joule / coulomb?



How does the resistance of a wire depend on its length?



How does the resistance of a wire depend on its area of cross – section?



When are resistors said to be connected in series?



When are resistors said to be connected in parallel?



Why is tungsten suitable for making the filament of a bulb?



Why is tungsten not used as a fuse wire?



Alloys are preferred over metals for making the heating elements of heaters. Why?



How is the direction of electric current related to the direction of flow of electrons in a wire?



Should the heating element of an electric iron be made of iron, silver or nichrome wire?







QUIZ – WHO AM I



I am equal to the charge carried by 6.25 x 1018 electrons.



I am the rate of flow of charge through any section of a conductor.



I am same as coulomb/second.



I am closed path along which electric charges can flow.



I am equal to the work done per unit charge from point to another.



I am same as joule/coulomb.



I oppose the flow of charges through any conductor.



I am same as volt/ampere.



I relate potential difference with current for a given resistance.



I am used to measure potential difference between two points of a circuit.



CROSSWORD PUZZLE- ELECTRICITY





Across
7. Unit of electrical power, named after the Scottish inventor of the steam engine
8. a rotating machine that transforms electrical energy into mechanical energy
9. The kind of electricity you create by rubbing a balloon on your head
13. Atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons
14. Emission of radiant energy in the form of waves or particles
15. It transmits electricity, like copper
16. Opposition to the passage of an electric current
19. Elementary particle consisting of a charge of negative electricity
20. Smallest particle of an element that can exist either alone or in combination
21. Uncharged elementary particle
22. Electric potential or potential difference

Down

1. Elementary particle that carries a positive charge
2. Electromagnetic radiation in the wavelength range including infrared, visible, ultraviolet, and X-rays
3. Device for making, breaking, or changing the connections in an electrical circuit
4. Flash produced by a discharge of atmospheric electricity
5. Complete path of an electric current including the source of electric energy
6. Inventor of the electric light bulb
10. Force acting on particles of matter, tending to draw them together
11. Electrical charge with more protons than electrons
12. Electrical charge with more electrons than protons
15. Electrical flow through a conductor
17. Definite quantity of electricity
18. Unit of electrical resistance


ANSWERS - ELECTRICITY CROSSWORD





MAGNETIC EFFECTS OF ELECTRIC CURRENT

KEY CONCEPTS & GIST OF THE LESSON


  • Magnet: (i) is an object that attracts objects made of iron, cobalt & nickel. (ii) Comes to rest in North-South direction, when suspended freely.




  • Magnets are used: (i) In radio & stereo speakers, (ii) In refrigerator doors, (iii) on audio & video cassettes players, (iv) On hard discs & floppies of computers & (v) in children’s toys.




  • Magnetic field: The area around a magnet where a magnetic force is experienced is called a magnetic field. It is a quantity that has both direction & magnitude.




  • Magnetic field lines: Magnetic field is represented by field lines. They are lines drawn in a Magnetic field along which a North magnetic pole moves. Magnetic field lines are called as Magnetic lines of force.

Refer to figure 13.3 & 13.4 page no. 225 of N.C.E.R.T Text book)


  • Properties of Magnetic field lines:

        1. They do not intersect each other.

(ii) It is taken by convention that magnetic field lines emerge from

North pole and merge at the South pole. Inside the magnet, their

direction is from South pole to North pole. Therefore magnetic field

lines are closed curves.



  • Magnetic field lines due to a current through a straight conductor (wire)- consist of series of concentric circles whose direction is given by the Right hand thumb rule.

  • Right hand thumb rule: If a current carrying straight conductor is held in your right hand such that the thumb points towards the direction of current, then the wrapped fingers show the direction of magnetic field lines.

(Refer to figure 13.7, page no. 228 of N.C.E.R.T Text book)

  • Magnetic field lines due to a current through a circular loop

(Refer to figure 13.8, page no. 228 of N.C.E.R.T Text book)

  • The strength of the magnetic field at he centre of the loop(coil)depends on:

      1. The radius of the coil- The strength of the magnetic field is inversely proportional to the radius of the coil. If the radius increases, the magnetic strength at the centre decreases.

      2. The number of turns in the coil: As the number of turns in the coil increase, the magnetic strength at the centre increases, because the current in each circular turn is having the same direction, thus the field due to each turn adds up.

      3. The strength of the current flowing in the coil: as the strength of the current increases, the strength of thee magnetic fields also increases.




  • Solenoid: (Refer to figure 13.10, page no. 229 of N.C.E.R.T Text book)

  • (i) A coil of many turns of insulated copper wire wrapped in the shape of a cylinder is called a Solenoid. (ii) Magnetic field produced by a Solenoid is similar to a bar magnet.

(iii) The strength of magnetic field is proportional to the number of turns & magnitude of current.

  • Electromagnet: An electromagnet consists of a long coil of insulated copper wire wrapped on a soft iron core.

(Refer to figure 13.11, page no. 229 of N.C.E.R.T Text book)


  • Fleming’s Left hand rule: Stretch the thumb, forefinger and middle finger of left hand such that they are mutually perpendicular. Forefinger points in the direction of magnetic field and centre finger in the direction of current, then the thumb gives the direction of force acting on the conductor.

(Refer to figure13.13, page no. 231 13.13 of N.C.E.R.T Text book)


  • Electric motor: A device that converts electric energy to mechanical energy.

(Refer to figure 13.15, page no. 232 of N.C.E.R.T Text book)


  • Principle of Electric motor: When a rectangular coil is placed in a magnetic field and a current is passed through it, force acts on the coil, which rotates it continuously. With the rotation of the coil, the shaft attached to it also rotates.



  • Electromagnetic induction: Electricity production as a result of magnetism (induced current) is called Electromagnetic induction.




  • Fleming’s Right hand rule: gives the direction of induced current.

Stretch the thumb, forefinger and middle finger of right hand such that they are mutually

perpendicular. Forefinger points in the direction of magnetic field and centre finger in the

direction of induced current, then the thumb gives the direction of motion of the conductor.


  • Electric generator: A devise that converts mechanical energy to electric energy.

(Refer to figure 13.19, page no. 236 of N.C.E.R.T Text book)

Electric generator is of two types- (i) A.C generator (ii) D. C generator




  • Principle of Electric generator: Electromagnetic induction




  • Domestic electric circuits: (Refer to figure 13.20, page 238 of N.C.E.R.T Text book)

  • We receive electric supply through mains supported through the poles or cables. In our houses we receive AC electric power of 220V with a frequency of 50Hz.

The 3 wires are as follows- (i) Live wire- (Red insulated, Positive)

(ii) Neutral wire- (Black insulated, Negative)

(iii) Earth wire- (Green insulated) for safety measure to ensure

that any leakage of current to a metallic body does not give

any serious shock to a user.


  • Short circuit: is caused by touching of live wires and neutral wire

  • Fuse: is a protective device used for protecting the circuits from short circuiting and over loading

  • Important diagrams-

  1. Magnetic field lines around a bar magnet.

  2. Right hand thumb rule

  3. Magnetic field lines through and around a current carrying solenoid.

  4. An electromagnet.

  5. A simple electric motor

  6. Electric generator

  1. Magnetic field lines around a bar magnet

  2. Direction of electric current in a simple electric circuit.

  3. Direction of Magnetic field lines depends on the direction of electric current.


MIND MAP

MAGNETIC EFFECT OF ELECTRIC CURRENT

Safety measure

Fuse Earth wire



Magnet and its properties

Magnetic field lines & properties.

Right hand thumb rule





Domestic electric circuits



Fleming right hand rule.

Electromagnetic induction.

Generator



Solenoid

Fleming left hand rule

Electric motor






Electro magnet


FORMATIVE ASSESSMENT I

Q. PAPER

MARKS-30 TIME- 70 MINUTES


Instructions:

  • Questions : 1 to 5 – 1 Mark each

  • Questions : 6 to 9 – 2 Marks each

  • Questions : 10 to 13 – 3 Marks each

  • Question 14 – 5 Marks



State two uses of electromagnet.



An electron moving along X – axis in a magnetic field along Y – axis. In which direction will the electron deflected.



State Fleming’s left hand rule.



What is the importance of earth wire?



Should a copper wire be used as a fuse wire? If not, why?



Give two points of difference between and electromagnet and permanent magnet.



Draw the lines of force indicating field direction of the magnetic field through and around

  1. Single loop of wire carrying electric current.

  2. A solenoid carrying electric current.



What id magnetic field? How is the direction of magnetic field at a point determined?



Give four features of domestic electric wiring.



Draw a schematic diagram of domestic wiring system and write its main features.



Match the following:




A

B




  1. Right hand thumb rule

  1. Force on a conductor in a magnetic field




  1. Fleming’s left hand rule

  1. Direction of magnetic field of straight conductor




  1. Fleming’s right hand rule

  1. Direction of induced current in conductor







  1. Polarity of any end of a solenoid.



  1. Draw a labelled diagram to show how electro – magnet is made.

  2. What is the purpose of soft iron core in making electromagnet?



Write two differences between AC and DC current and draw diagram also.



  1. Write principle of electric generator.

  2. Explain construction and working of generator.

  3. Draw labelled diagram of electric generator.


HOTS QUESTIONS (SOLVED)

  1. On what effect of an electric current does an electromagnet work?

A. Magnetic effect of electric current

  1. What is the frequency of AC (Alternating Current) in India?

  1. 50Hz

  1. On what effect of an electric current does a fuse work?

A. Heating effect of electric current
HOTS QUESTIONS (UNSOLVED)

  1. Name the sources of direct current.

  2. Why don’t two magnetic lines intersect each other?

  3. What is the role of split ring in an electric motor?

  4. What is an earth wire?

MAGNETIC EFFECT

ORAL QUESTIONS



  1. What are magnets?

  2. What are natural magnets?

  3. What is the meaning of the word lodestone?

  4. What is the origin of the word magnetism?



  1. State the law of magnetic poles.

  2. What is the surer test of magnetism?

  3. What happens if we break a magnet into two pieces?

  4. Is it possible to obtain isolated north and south poles?



  1. What is magnetic line of force?

  2. Can two magnetic lines of force intersect? Give reason.

  3. Magnetic lines of force are endless. Comment.

  4. How do the field lines of the regions of strong field different from those of weak field?



  1. What is a solenoid?

  2. Is the magnetic field of a solenoid similar to that of a bar magnet?

  3. State the two factors by which the strength of magnetic field inside a solenoid can be increased.

  4. How will you determine the direction of the magnetic field due to a current – carrying solenoid?



  1. What is an electromagnet?

  2. What is the effect of placing an iron core in a solenoid?

  3. What type of core should be used inside a solenoid to make an electromagnet?

  4. Give two advantages of electromagnets.





ORAL QUESTIONS



What important observation did Oersted make in his experiments with current carrying conductors?



How can you locate a current – carrying wire concealed in a wall?



A freely suspended magnet always points along north – south direction. Why?



What type of core should be used inside a solenoid to make an electromagnet?



Name the SI unit of magnetic field.



What is the principle of an electric motor?



A generator converts energy from one form to another. What is this energy conversion?



Which wire (live, neutral or earth) goes through the switch?



Are different appliances connected in series or parallel in a house?



What is the colour convention for live, neutral and earth wires?

PUZZLE




Across

  1. A method preventing electric shock due to touching of live wire with the metallic body of an appliance.

  2. A device to convert electrical energy into mechanical energy.

  3. A device to convert mechanical energy into electrical energy.

  4. SI unit of magnetic field.

Down

  1. A material having attractive and directive properties.

  2. A temporary magnet.

  3. A device to protect a circuit from overloading.




























2M5






































































































































































1E6




























3G




4



































































































































































7










































































































































































































































































































































ANSWERS-MAGNETISM


SOURCES OF ENERGY

KEY CONCEPTS & GIST OF THE LESSON


  • Characteristics of a good fuel:

      1. High calorific value

      2. Less smoke

      3. Less residue after burning

      4. Easy availability

      5. Inexpensive

      6. Easy to store and transport




  • Fossil fuels: were formed millions of years ago, when plants and animal remains got buried under the earth and were subjected to high temperature and pressure conditions. E.g.: Coal, Petroleum, etc. These fossil fuels are non renewable sources of energy and cause environmental problems due to pollution.

  • Thermal power plants:

  1. Use coal, petroleum and natural gas to produce thermal electricity.

  2. Electricity transmission is very efficient.

  3. The steam produced by burning the fossil fuels runs the turbine to produce electricity




  • Hydro power plant:

(Refer to figure 14.3, page no. 246 of N.C.E.R.T Text book)

  1. It is the most conventional renewable energy source obtained from water falling from a great height.

  2. It is clean & non polluting source of energy.

  3. Dams are constructed to collect water flowing in high altitude rivers. The stored water has a lot of potential energy.

  4. When water is allowed to fall from a height, potential energy changes to kinetic energy, which rotates the turbines to produce electricity.

  • Disadvantages of Hydro power plant:

  1. Highly expensive to construct.

  2. Dams cannot be constructed on all river sites.

  3. Large areas o human habitation and agricultural fields get submerged.

  4. People face social and environmental problems.




  • Non conventional sources:

(1) Bio mass:

      • It is the source of the conventionally used fuels that are used in our

country. E.g.: Cow dung cakes, fire-wood, coal, charcoal

      • Bio gas: It is a mixture of gases produced during decomposition of bio mass in the absence of Oxygen. (Anaerobic Respiration). Methane is the major component of bio gas.

      • Bio gas plants: Animal dung, sewage, crop residues, vegetable wastes, poultry droppings, etc. are used to produce Bio gas in Bio gas plants.

      • (Refer to figure 14.4, page no. 247 of N.C.E.R.T Text book)

    1. Wind energy:

      • It can be converted into mechanical and electrical energy.

      • Kinetic energy of the wind is used in running of wind mills, which are used to lift water, grind grains, etc.

      • Wind mill-(Refer to figure 14.5, page no. 247 of N.C.E.R.T Text book)

      • Advantages: (i) Eco friendly (ii) Renewable

      • Disadvantages: (i) Wind speed not uniform always.

(ii) Needs a large area to erect series of wind mills.

(iii) Big amount of investment is needed.

(iv) Out put is less as compared to investment


    1. Solar energy:

      • Solar radiations can be converted electricity through solar cells (photovoltaic cells).

      • Photovoltaic cells convert solar radiations directly into electricity through silicon solar cells.

      • Solar cells arrange on a large flat sheets form a solar panel.

      • Solar cookers are painted black from outside and a large glass plate to trap solar radiations by green house effect.

      • (Refer to figure 14.6, page no. 249 of N.C.E.R.T Text book)

      • Advantages of Solar cookers:

(i) Eco friendly

(ii) Renewable

(iii) Used in rural areas.

(iv) Retains all the nutrients in food due to slow cooking.



      • Disadvantages of solar cooker:

(i) Silicon cells are expensive.

(ii) Solar radiations are not uniform over earth’s surface.

(iii) Cannot be used at night or on cloudy days.

(iv) Cannot be used to make chapattis for frying as these

require a temperature of 1400C or more.

(Maximum temperature of 1000C only can be

achieved in a solar cooker)


      • Other solar devices- Solar water heater, Solar furnace

    1. Geo thermal energy:

    1. Energy harnessed from the heat of the sun is called Geo thermal energy.

    2. Magma is formed when this heat melts the rocks. The molten rocks and hot gases are called magma

    3. The magma gets collected at some depths below the earth’s surfaces. These places are called ‘Hot spots”

    4. When underground water comes in contact these hot spots, it changes into steam, which can be used to generate electricity.

      • Advantages of Geo thermal energy:

  1. Renewable

(ii) Inexpensive

      • Disadvantages of Geo thermal energy:

  1. Only few sites available for harnessing energy.

  2. Expensive

    1. Nuclear energy:

(i) Energy released when some changes take place in the nucleus of the atom of a

substance, is called Nuclear energy.

(ii) It is used for heat generation, fuel for marine vessels.


      • Advantages of Nuclear energy:

      1. Alternative source of energy due to depletion of fossil fuels.

      2. From a small amount of fuel, a large amount of energy is released.

      • Disadvantages of Nuclear energy:

  1. Risk of nuclear waste leakage

  2. High cost of setting up of nuclear plant

      1. Pollution of environment.

    1. Energy from the sea-

(A) Tidal energy: Locations in India – Gulf of Kutch, Gujrat & W. Bengal

(i) Depends upon harnessing the rise and fall of sea level due to tidal action.

(ii) Dams are constructed across a narrow part of sea and turbine converts tidal

energy into electrical energy.

Disadvantages: Uniform tidal action is not seen

(B) Wave energy:

(i) Kinetic energy of the waves of sea are used to rotate turbines..

(ii) These turbines generate electrical energy




  • Important diagrams-

  1. Hydro power plant

  2. Bio gas plant

  3. A wind mill

  4. A solar cooker


MIND MAP

Characteristics of good fuel

Fuel


Sources of energy

Non renewable

(conventional)



Fossils fuels

coal

Wind mill




Renewable

(non –conventional)



Geothermal



Nuclear

Solar

Wind




Biomass

Water




Petroleum



Nuclear power plant

Solar cooker

Biogas plant

Hydro power plant




Thermal power plant


FORMATIVE ASSESSMENT I

Q.PAPER

MARKS-30 TIME- 70 MINUTES


Instructions:

  • Questions : 1 to 5 – 1 Mark each

  • Questions : 6 to 9 – 2 Marks each

  • Questions : 10 to 13 – 3 Marks each

  • Question 14 – 5 Marks



Name the component of sunlight, exposure to which may cause skin cancer.



Flowing water possess which type of energy.



Name one place in India where wind energy power station is installed.



What is a solar panel?



What type of energy transformation takes place during winding of spring of a clock?



Write two differences between renewable and non – renewable sources of energy.



What is the principle of solar cooker? Name two types of solar cooker.



Name any two types of harmful nuclear radiations emitted during nuclear fission.



What is thermal power plant? Where it is preferably situated?



What is the principle of solar cooker? Give two limitations and two advantages of solar cooker.



Name the fuel for hydro power plant. Mention two advantages and disadvantages of producing electricity at the hydro power plant.



Explain why:

  1. It is difficult to burn a piece of wood fresh from a tree.

  2. Pouring dry sand over the fire extinguishes it.

  3. It is difficult to use hydrogen as source of energy.



What are the different types of energies obtained from sea? Explain.



  1. What is a principle of Biogas?

  2. Explain it working in brief.

  3. Draw a labelled diagram of biogas.

HOTS QUESTIONS (SOLVED)


  1. Name the materials used for making solar cells.

A. Silicon, Germanium and Selenium

  1. What fraction of solar energy reaches the earth’s surface?

A. 47%

  1. Name the process that produces a large amount of energy in the sun.

  1. Nuclear fusion




  1. Why is biogas called a clean fuel?

A. Because it- (i) leaves no ash (ii) does not cause pollution (iii) does not produce any

poisonous gas.



HOTS QUESTIONS (UNSOLVED)

  1. What is the use of black painted surface in solar heating devises.

  2. Why are bio gas plants considered to be boon to the farmers? Give reason.

  3. Hydroelectricity generated at a dam may be considered another form of solar energy. Why?

  4. How is the slurry left over after the generation of biogas in biogas plant used?

  5. Why is charcoal considered to be a better fuel than wood?

  6. Why a solar cooker cannot be used for frying or making chapattis?

  7. In parabolic reflector type coolers, even temperature up to 1800C- 2000C can be attained. How?

  8. Modern chulahs are more efficient than traditional chulahs. Why?

  9. How is hydro energy converted into electrical energy?

  10. Explain, why only a part of the solar energy that strikes the upper regions of atmosphere reaches the surface of the earth?




ENERGY

ORAL QUESTIONS (CONVERSATION TYPE)



  1. What is a good source of energy?




  1. Name one good source of energy.




  1. It is a renewable source of energy?




  1. Is it conventional or non – conventional source of energy?




  1. What other name is give to it?




  1. What is a fossil fuel?




  1. Name any other two fossil fuels.



  1. Which is the ultimate source of all forms of energy?




  1. Can you explain?




  1. Name some renewable source of energy arising due to sun.




  1. Name some non – renewable source of energy arising due to sun.




  1. Why is the energy contained in fossil fuels considered due to sun’s energy?




  1. Name any source of energy not influenced by sun’s energy.



  1. What is the principle of nuclear energy?




  1. What are the kinds of nuclear reaction?




  1. Which of these can be used for destructive purposes?




  1. Which of these can be used to produce energy for common use?




  1. What is nuclear fission?




  1. Name two substances which are easily fissionable.




  1. What are these substances called?




  1. What is this phenomenon of breaking up of radioactive isotopes called?




  1. Name the rays emitted.







ORAL QUESTIONS



Which component of solar radiations produces heat?



Name a form of energy that can be harnessed from the oceans.



Name the main component of biogas.



Name a fuel which is considered cleaner that CNG.



What is common between an atom bomb and a nuclear reactor?



What is the main transformation of energy during working of a windmill?



What are the conditions to achieve nuclear fusion?













QUIZ



I am a force that cannot be created but my form may be changed.



I am an important part of the system that transforms that transforms K.E. / P.E. into electrical energy.



I have been used to produce energy for a long time and my origin is in the remains of plants and animals.



I used to thrown as a waste material for centuries. But I am given an honourable name and a useful work to perform.



I have a huge body capable of eating water from any source with a decorative head called Hydroelectric power station.



I resemble a fossil fuel but find use as self sustained source of energy especially in rural areas.



I produce a chain of reactions each step capable of producing tremendous amount of energy.



I am associated with nuclear reactions but deliver heat in critical conditions.



I am the lightest fuel with a large potential as a source of energy.



I deliver hot springs with taking any energy from man – made sources or sun.







PUZZLES



Across

  1. A type of metal that allows only partial current to pass (13)

  1. A device to harness kinetic energy of wind (8)

Down

  1. Vegetable and animal waste (7)

  1. Process to increase percentage of fissionable material (10)



























































































B2





























































4








































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Across

  1. Trapped energy inside earth (10)

  1. A substance which slows down the speed of neutrons in nuclear reactor (9)

Down

  1. Liquid fossil fuel (9)

  1. Isotope commonly used in nuclear reactor (7)

































































































3
































































4


































2




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