A closed copper coil of area 1 . 0 m 2 placed perpendicular to a magnetic field of 0 . 10 T is rotated through 180 ° in 0 . 01 s . Find the induced emf and induced current in the coil whose resistance is 2 . 0 Ω . If the coil is open somewhere, then what will be the emf and the current?

(i) When the coil is closed. E = - N d ϕ d t = + 1 × 2 × 0 . 10 × 1 0 . 01 = 20 V 1 = E R = 20 2 = 10 A Ans: E = 20 V I = 10 A (ii) When the coil is open, E = 20 V I = 0 is the coil is open circuit.

A coil of area 500 cm 2 and 2000 turns is kept normal to a magnetic field of 4 × 10 - 5 Wb m - 2 . It is rotated through 180 ° in 0 . 1 s . (i) Calculate the average induced emf.

E = - N d ϕ d t = + 2 N B A d t = + 2 × 2000 × 4 × 10 - 5 × 500 × 10 - 4 0 . 1 = 80 × 10 - 3 Answer: E = 80 mV = 0 . 08 V .

A coil of area 500 cm 2 and 2000 turns is kept normal to a magnetic field of 4 × 10 - 5 Wb m - 2 . It is rotated through 180 ° in 0 . 1 s . (ii) If the total resistance of the circuit be 20 Ω , calculate the induced charge.

Q i n d = I i n d × Δ t = E R . ∆ t = 80 × 10 - 3 × 0 . 1 20 = 0 . 4 mC Ans: Induced charge = 4 × 10 - 4 C = 0 . 4 mC

What are eddy currents?

Eddy currents : (Also called Foucault's Currents) Eddy currents are the loop of electrical currents induced within the conductors by magnetic field in the conductor, and it is perpendicular to magnetic field, as per Faraday's law of induction.

How does the self-inductance of a coil depend on the number of turns of the coil?

Self-inductance(L) of a coil depend on the number of turns(N) of the coil. Where self inductance is directly proportional to square of the number of turns. L ∝ N 2 . Here self inductance is represented by L, and Number of turn is represented by N.

EASY

12th ICSE

IMPORTANT

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A $28$ turn coil with average diameter of $0.02 m$ is placed perpendicular to a magnetic field of $8000 T$ . If the field changes to $3000 T$ in $4 s$ , what is the magnitude of the induced emf? $(π = 22 / 7)$

Important Questions on Electromagnetic Induction

EASY

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 11 - Electromagnetic Induction>QUESTIONS>Q 7

A closed copper coil of area

1.0 m^{2}

placed perpendicular to a magnetic field of

0.10 T

is rotated through

180 °

0.01 s

. Find the induced emf and induced current in the coil whose resistance is

2.0 Ω

. If the coil is open somewhere, then what will be the emf and the current?

EASY

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 11 - Electromagnetic Induction>QUESTIONS>Q 8

A coil of area

500 {cm}^{2}

and

2000

turns is kept normal to a magnetic field of

4 \times 10^{- 5} Wb m^{- 2}

. It is rotated through

180 °

0.1 s

. (i) Calculate the average induced emf.

MEDIUM

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 11 - Electromagnetic Induction>QUESTIONS>Q 8

A coil of area $500 {cm}^{2}$ and $2000$ turns is kept normal to a magnetic field of $4 \times 10^{- 5} Wb m^{- 2}$ . It is rotated through $180 °$ in $0.1 s$ .

(ii) If the total resistance of the circuit be $20 Ω$ , calculate the induced charge.

EASY

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 11 - Electromagnetic Induction>QUESTIONS>Q 9

A rectangular loop of sides

10 cm \times 3 cm

with a small cut is moving out of a uniform magnetic field of

0.5 T

directed normal to the loop. Compute the voltage induced across the cut, if the velocity of the loop is

1 cm s^{- 1}

in a direction (i) normal to the longer side ?

EASY

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 11 - Electromagnetic Induction>QUESTIONS>Q 9

A rectangular loop of sides

10 cm \times 3 cm

with a small cut is moving out of a uniform magnetic field of

0.5 T

directed normal to the loop. Compute the voltage induced across the cut, if the velocity of the loop is

1 cm s^{- 1}

in a direction (ii) normal to the shorter side of the loop. For how long does the induced voltage last in each case?

MEDIUM

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 11 - Electromagnetic Induction>QUESTIONS>Q 10

A long solenoid of radius

0.01 m

has

600

turns per metre. A smaller coil of

100

turns is wrapped closely around the centre of the bigger solenoid. If the current in the solenoid rises from zero to

2 A

1 ms

, find the emf induced in the smaller coil.

EASY

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 11 - Electromagnetic Induction>QUESTIONS>Q 11

A small loop of area

20 {cm}^{2}

is placed inside a long solenoid having

1500

turns per metre, normal to the axis of the solenoid. Find the voltage induced in the loop while the current in the solenoid is changed from

2 A

4 A

0.1 s

EASY

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 11 - Electromagnetic Induction>QUESTIONS>Q 12

50 cm

long wire is moving in a uniform magnetic field of

0.8 N A^{- 1} m^{- 1}

with a velocity of

2 {ms}^{- 1}

perpendicular to both its length and the magnetic field. Calculate the induced emf in the wire. If the wire be moving parallel to the field, what will be the value of the induced emf?

A 28 turn coil with average diameter of 0.02 m is placed perpendicular to a magnetic field of 8000 T. If the field changes to 3000 T in 4 s, what is the magnitude of the induced emf? π=22/7

Important Questions on Electromagnetic Induction

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A $28$ turn coil with average diameter of $0.02 m$ is placed perpendicular to a magnetic field of $8000 T$ . If the field changes to $3000 T$ in $4 s$ , what is the magnitude of the induced emf? $(π = 22 / 7)$