NEET Electromagnetic Induction — Set 22

Question 1

A coil of 70 turns experiences a magnetic flux change from 0 to 0.02 Wb in 0.04 s. What is the induced emf?

Accepted Answer

$ \varepsilon = N \frac{\Delta \Phi}{\Delta t} $. $ \Delta \Phi = 0.02 \, \text{Wb} $, $ \Delta t = 0.04 \, \text{s} $, $ N = 70 $. $ \varepsilon = 70 \times \frac{0.02}{0.04} = 70 \times 0.5 = 35 \, \text{V} $.

Question 2

A circular loop of radius 12 cm is deformed into a straight wire in a 0.2 T field in 0.5 s. What is the induced emf?

Accepted Answer

Initial flux: $ \Phi = B A = 0.2 \times \pi \times (0.12)^2 = 0.00904 \, \text{Wb} $. Final flux = 0. $ \varepsilon = \frac{\Delta \Phi}{\Delta t} = \frac{0.00904}{0.5} = 0.01808 \, \text{V} \approx 0.018 \, \text{V} $.

Question 3

A coil of self-inductance 1.0 H has its current decreased from 5 A to 2 A in 0.15 s. What is the magnitude of the induced emf?

Accepted Answer

$ \varepsilon = L \frac{\Delta I}{\Delta t} $. $ \Delta I = 2 - 5 = -3 \, \text{A} $, $ \Delta t = 0.15 \, \text{s} $. $ \varepsilon = 1.0 \times \frac{-3}{0.15} = 1.0 \times (-20) = -20 \, \text{V} $, magnitude = 20 V.

NEET Physics: Electromagnetic Induction — Practice Set 22

Q1. A coil of 70 turns experiences a magnetic flux change from 0 to 0.02 Wb in 0.04 s. What is the induced emf?

Q2. A circular loop of radius 12 cm is deformed into a straight wire in a 0.2 T field in 0.5 s. What is the induced emf?

Q3. A coil of self-inductance 1.0 H has its current decreased from 5 A to 2 A in 0.15 s. What is the magnitude of the induced emf?

Q4. A solenoid’s current is switched off suddenly. What causes sensitive instruments nearby to be at risk of damage?

Q5. A square loop of side 20 cm rotates at 20 rad/s in a 0.15 T field. What is the maximum emf induced?

Q6. A wheel with 7 spokes of 0.45 m each rotates at 36 rpm in a 0.6 T field. What is the induced emf?

Q7. A coil of 130 turns and area 0.03 m² is rotated at 30 Hz in a 0.08 T field. What is the maximum emf?

Q8. A coil of 230 turns rotates at 85 rad/s in a 0.03 T field. If the area is 0.02 m², what is the maximum emf?

Q9. A coil of 170 turns and area 0.07 m² is in a field that decreases from 0.1 T to 0 in 0.5 s. What is the induced emf?

Q10. A solenoid of 500 turns per meter and area 0.01 m² has a current change from 3 A to 0 A in 0.5 s. What is the self-induced emf? (\( \mu_0 = 4\pi \times 10^{-7} \, \text{H/m} \))