# Class 9 FRANK Solutions Physics Chapter 8 - Electricity and Magnetism

Practise Frank Solutions for ICSE Class 9 Physics Chapter 8 Electricity and Magnetism to get a grasp of concepts better. Learn about the different types of electric charges, and the differentiating points between a secondary cell and a primary cell. Our reference solutions created by our experts for your textbook questions will guide you in your study plan.

To score top marks, TopperLearning provides not only Frank solutions but also ICSE Class 9 Physics Selina solutions. For evaluating your understanding of electricity and magnetism, attempt our online practice tests and use our other assessment resources for effective self-study sessions.

## Electricity and Magnetism Exercise 323

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(a) Primary cells cannot be charged again while secondary cells can be charged again and again.

(b) In primary cells, chemical reaction is irreversible while in secondary cells , chemical reaction is reversible.

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(a) Primary cells cannot be charged again while secondary cells can be charged again and again.

(b) In primary cells, chemical reaction is irreversible while in secondary cells , chemical reaction is reversible.

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So, n = I.t / e = 1. 1 / 1.6 x 10

^{-19}= 6.25 x 10

^{18}

So, 6.25 x 10

^{18}will be the number of electrons.

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The effect to rate of flow of current by the wire is called its electrical resistance. Its S.I unit is ohm.

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(i) Length of the wire

(ii) Cross-section of the wire

(iii) Temperature of the wire.

(iv) Material of the wire.

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A variable resistance is a device used to change the resistance and hence the current flowing through a circuit; without changing the voltage.

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The magnets (pieces of lodestone) found in nature is called natural magnet. The properties of magnet are : (a) Attractive property (ii) Directive property (iii) like poles repel while unlike poles attract.

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## Electricity and Magnetism Exercise 324

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(ii) The B will be charged by the charging by contact. The charge on A will spread on B.

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(i) Bring a positively charged rod near the cap of an electroscope. The cap will acquire the negative charge on it by induction. The leaves will diverge

(ii) Earth the electroscope by touching the cap will finger.

(iii) Remove the finger and keep the positively charged rod as such.

(iv) Now, take away the rod. The leaves will diverge because of charges induced by induction..

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(b)

(i) Resistance of the conductor: It is the property of the conductor by virtue of which it obstructs the flow of current in the circuit.

(ii) Potential Difference: It is defined as the amount of work done in moving a charge from one point to another .

(iii) Open Circuit: In the circuit, if the switch is off or the wire is cut then flow of current in circuit stops and we say that its an open circuit.

(iv) Closed Circuit: The circuit in which current flows without any obstruction then it's a closed circuit.

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(ii) When the two bulbs will be connected in parallel then resistance of circuit will decrease so the bulbs brightness will increase.

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(a) Conductors allow passing of electric current through it. Insulator does not allow passing of current through it.

(b) Silver, Gold are good examples of conductor of electricity . Rubber, Cotton are good examples of insulators.

(ii) Flow of electrons is the flow of negative charges inside the conductor while flow of conventional current is the flow of positive charges inside a conductor.

(iii) Primary cells are the cells in which chemical reaction is irreversible so they can't be charged again and again. While , secondary cells are the cells in which chemical reaction is reversible and can be charged again and again.

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(i) Like poles of magnet repel each other while unlike poles attract.

(ii) Magnet have an attractive property means it attract the magnetic material towards it.

(iii) Magnet have the directive property means when it is held freely , it always point towards north-south direction.

(b) The Laws of Magnetism: Like poles repel each other and unlike poles attract each other.

(c) (i) Magnetic materials get attracted towards the magnet but non-magnetic materials does not get attracted towards the magnet.

(ii) Natural magnets are the pieces of lodestone which are found in nature while artificial magnet is the magnetized piece of iron or steel.

(iii)Iron has high susceptibility and low retentivity means it acquires the magnetism faster and removes it soon as well. While , steel has low susceptibility and high retentivity.

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## Electricity and Magnetism Exercise 325

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b)(i) If we had a magnet then we will bring the magnet near to steel , if there is force of repulsion or attraction is experienced then steel was magnetized otherwise not.

(ii) We will held the steel freely, if it points to north-south direction only then it is magnetized otherwise not.

c) (i) Magnetic Meridian: It is the vertical plane containing the magnetic axis of a freely suspended magnet at rest under the earth's field.

(ii) Geographic Meridian: It is the vertical plane containing the geographic north and south poles of the earth and passing through the given place in the surface of earth.

(iii)Angle of declination: The angle between geographic and magnetic meridian is called angle of declination.

(iv)Angle of Dip: The angle between the horizontal and earth's magnetic field is known as angle of dip.

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(ii) The rubbed ebonite rod contains more electrons so it acquires the negative charge so a charged is acquired by it. But, in the rubbed metal rod , electrons are transferred but through hands and body they pass to the earth so no charges will be there while metal rod is held in hand.

(iii)Soft iron is used to make electromagnets because it has high susceptibility and low retentivity , it get magnetized very faster and loses magnetism as soon as the inducing magnet is removed.

(iv)Two steel needles hanging from the lower end of the vertical bar magnet do not hang vertical but will diverge because they got the like poles on it and like poles repel each other so they diverge.

(v)If magnetic material is brought near to the magnet then it get attracted although its not magnetized but the magnetic material will be repelled only in case it is magnetised. So repulsion is the sure test of magnetism.

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(1) It leads to large catchment area being submerged

(2) displacement of people from their places.

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(1) Use the improved cook stove which will save the bio-mass energy

(2) Use the improved solar panels and solar furnaces.

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(1) control and keep an eye on consumption pattern

(2) develop appliances suitable for the energy change

(3) organize posters and slogans for developing awareness in society.

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(b) At Home : Use of bio energy for cooking and lightening, use CFLs instead of filament bulbs, keep the electrical appliances off after the needed period of time.

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