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Correct option is  B) AC

C) electro magnetic induction

Correct option is  A) 220 A

A) Both statements are true

C) Faraday’s law

Correct Answer is: (b, c, & d)

The resistance of circuit decreases, and a sudden flow of large current heats up the live wire and vapourises the metal. This causes spark. The metal of wire becomes very hot and naturally emits white light.

(a) Self induction: “The phenomenon due to which a current flowing through a part of coil, induces an e.m.f. in the rest of coil due to change in magnetic flux is called self induction.” 

(b) Eddy currents : “The current produced in any metallic conductor when a magnetic flux is changed around it is called Eddy Current.

(1) A momentary deflection of pointer of galvanometer towards right side is seen. 

(2) More the speed, more is the deflection. 

(3) When magnet is stopped with in the coil, the pointer of galvanometer comes to zero position. 

(4) Deflection of pointer of galvanometer is in opposite direction to towards the left. 

(2) Then more powerful magnet is used deflection of pointer will be more.

(a) Fleming’s right hand rule

In generators, mechanical energy is converted into electrical energy.

The polarity of a permanent magnet cannot be reversed.

D) Electric motor

Brushes B₁ and B₂ are used to achieve this

Correct option is: C) generator

I don't know the answer

Correct Answer is: (c) perpendicular to the plane of the paper, directed into the paper

The armature of the electric bell is made of soft iron. This is because soft iron when magnetised is quickly demagnetised when the circuit is broken. Steel armature might lock up the circuit and the bell may not work.

Correct Answer is: (a) must be zero 

Lenz law : The induced current will appear in such a direction that it opposes the change in the flux in the coil. 

Explanation :

1. We know that when a bar magnet is pushed towards a coil with its north pole facing the coil an induced current is set up in the coil. 

2. Let the direction be clockwise then current carrying loop behaves like a magnet with its south pole facing the north pole of bar magnet. 

3. In such a case, the bar magnet attracts the coil. Then it gains kinetic energy. This is contradictory to conservation of energy. 

4. Hence our assumption is wrong. So correct induced current direction is anti-clockwise.

5. Let us see a case where the bar magnet is pulled away from the coil with the north pole facing the coil. In such case, the coil opposes the motion of bar magnet to balance the conversion of mechanical energy into electric energy. 

6. It happens only when the north pole of the magnet faces the south pole of the coil. 

7. So, the direction of induced current in the coil must be in anticlockwise direction. 

8. In simple terms, when flux increases through coil, the coil opposes the increase in the flux and when flux decreases through coil, it opposes the decrease in the flux. This is Lenz law.

The effect of magnetic field on moving charges has been used to build machines, called particle accelerators. 

Ex: Cyclotron.

In the process of electrolysis, D.C. is used.

The ratio of magnetic force to electric force is very negligible.

In domestic circuits, the series arrangement is not used.

• The cost of generation of A.C is less than the cost of generation of D.C.
• A.C can be transmitted to distant places without much loss of electric power than D.C.
• A.C can be easily connected to D.C.
• A.C is more dangerous than D.C.

1. Motor.

2. 90°

3. By applying right hand rule to get the directions of magnetic force. At ‘AB’, the magnetic force acts inward perpendicular to field of the magnet and on ‘CD’, it acts outwards.

4. The net force on ‘AB’ is equal and opposite to the force on ‘CD’ due to external magnetic field because they carry equal currents in the opposite direction. Sum of these forces is zero. Similarly, the sum of the forces on sides ‘BC’ and ‘DA’ is also zero.

So, net force on the rectangular coil is zero.

A) generator

a) Number of turns 

b) Radius of the coil.

So that the mechanical energy spent in producing the change, is transformed into the electrical energy in form of induced current.

Correct Answer is: (b) can have the maximum magnitude 2Bir 

T = \(\frac{2\pi m}{B_q}\)

B = 2T ; Φ == ? ; A = 1.5 m² 

We know B = Φ/A

or Φ = BA = 2 × 1.5 =3 Webers

The maximum force acting on the current of both is 

F = Bil

a) Fuse 

b) Earthing

D) both B and C

1) When there is a continuous change of magnetic flux passing through a coil a current is generated in the coil. 

2) This process is used in 

1. Induction stoves 

2. Security checking entrance/exit doors. 

3. ATM cards scanners.