Direction of Induced EMF MCQ [Free PDF] – Objective Question Answer for Direction of Induced EMF Quiz

11. According to _________________ induced emf is equal to rate of change of magnetic flux.

A. Newton’s law
B. Lenz law
C. Faraday’s law
D. Coulomb’s law

Answer: C

According to Faraday’s law of electromagnetic induction, induced emf is equal to the rate of change of magnetic flux.

 

12. The emf induced in a coil having N turns is?

A. e = ϕ/t
B. e = N × ϕ/t
C. e = N × ϕ × t
D. e = N2 × ϕ × t

Answer: B

The emf induced in a coil having N turns is, e = N × ϕ/t. This is because, the emf in a single-coil is the flux linkage per unit time, that is, phi/t. Hence the flux induced in N turns is N × ϕ/t.

 

13. According to ____________________ induced emf oppose the cause due to which they are produced.

A. Newton’s law
B. Lenz law
C. Faraday’s law
D. Coulomb’s law

Answer: B

According to Lenz law, emf is induced in such a way that it opposes the cause due to which it is produced.

 

14. North pole induces __________

A. Clockwise current
B. Anti-clockwise current
C. Zero current
D. Infinite current

Answer: B

A north pole will always induce an anti-clockwise current whereas a south pole will always induce a clockwise current due to electromagnetic theory.

 

15. What is the principle of the transformer?

A. Gauss law
B. Coulomb’s law
C. Electromagnetic induction
D. Ampere’s law

Answer: C

In a transformer, flux in the secondary coil change due to the current in the primary coil, and hence current get induced in the secondary coil.

 

16. Voltage induced in the secondary coil of the transformer is given by _________

A. NP × VP/NS
B. NS × VP/NP
C. (NP/VP) × NS
D. NP/(VP × NS)

Answer: B

In transformer, VP/VS  = NP/NS

So, VS  = NS × VP/NP.

 

18. The force per unit length existing between two infinite parallel conductors is given by ___________

A. µ0i1i2/2πd
B. µ0i1i2/2d
C. µ0i1/2πdi2
D. µ0i1i2/d

Answer: A

Force of the infinite conductor is given by Bil if B, I, and l are mutually perpendicular

F/l = Bi = µ0i1i2/2πd

where d is the separation of two infinite parallel conductors.

 

19. If the radius of the current-carrying conductor increases, what is the effect on the force?

A. increases
B. decreases
C. remain same
D. become zero

Answer: C

Force of the infinite conductor is given by Bil if B, I, and l are mutually perpendicular

F/l = Bi = µ0i1i2/2πd

where

d is the separation of two infinite parallel conductors. It doesn’t depend on the radius of the conductor so the force remains the same.

 

20. If the current of the conductor increases, what is the effect on the force?

A. increases
B. decreases
C. remain same
D. become zero

Answer: A

The Force of the infinite conductor is given by Bil

where

B, I, and l are mutually perpendicular

F/l = Bi = µ0i1i2/2πd

where

d is the separation of two infinite parallel conductors. So, as current increases force increases.

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