NEET Electromagnetic Induction — Set 2

Question 1

A coil is placed in a uniform magnetic field of 0.5 T. The area of the coil is 0.04 m², and the angle between the field and the area vector changes from 0° to 90° in 0.2 s. What is the induced emf?

Accepted Answer

Initial flux: $ \Phi_i = B A \cos 0^\circ = 0.5 \times 0.04 \times 1 = 0.02 \, \text{Wb} $. Final flux: $ \Phi_f = B A \cos 90^\circ = 0.5 \times 0.04 \times 0 = 0 \, \text{Wb} $. $ \Delta \Phi = 0.02 - 0 = 0.02 \, \text{Wb} $, $ \Delta t = 0.2 \, \text{s} $. $ \varepsilon = -\frac{\Delta \Phi}{\Delta t} = \frac{0.02}{0.2} = 0.1 \, \text{V} $.

Question 2

A rod of length 0.4 m moves at 2 m/s in a 0.3 T field perpendicular to its length. What is the induced emf?

Accepted Answer

$ \varepsilon = B l v = 0.3 \times 0.4 \times 2 = 0.24 \, \text{V} $.

Question 3

A coil of 200 turns and area 0.04 m² is rotated at 50 Hz in a 0.1 T field. What is the maximum emf?

Accepted Answer

$ \omega = 2\pi v = 2\pi \times 50 = 100\pi \, \text{rad/s} $. $ \varepsilon_0 = N B A \omega = 200 \times 0.1 \times 0.04 \times 100\pi = 251.33 \, \text{V} \approx 251.3 \, \text{V} $.

NEET Physics: Electromagnetic Induction — Practice Set 2

Q1. A coil is placed in a uniform magnetic field of 0.5 T. The area of the coil is 0.04 m², and the angle between the field and the area vector changes from 0° to 90° in 0.2 s. What is the induced emf?

Q2. A rod of length 0.4 m moves at 2 m/s in a 0.3 T field perpendicular to its length. What is the induced emf?

Q3. A coil of 200 turns and area 0.04 m² is rotated at 50 Hz in a 0.1 T field. What is the maximum emf?

Q4. A rod rotates at 12 rad/s in a 0.5 T field. If the length from the axis to the tip is 0.9 m, what is the emf induced?

Q5. A solenoid with mutual inductance 0.4 H has a current change of 3 A/s in the primary coil. What is the induced emf in the secondary coil?

Q6. A rod rotates at 25 rad/s in a 0.5 T field. If the length from the axis to the tip is 0.7 m, what is the emf induced?

Q7. A solenoid of 650 turns and length 1.2 m induces an emf of 2.6 V in a nearby coil when its current changes from 2 A to 6 A in 0.4 s. What is the mutual inductance?

Q8. A coil of 180 turns rotates at 60 rad/s in a 0.03 T field. If the area is 0.02 m², what is the maximum emf?

Q9. A coil of 110 turns and area 0.035 m² is in a field that decreases from 0.09 T to 0 in 0.5 s. What is the induced emf?

Q10. A loop of 0.28 m × 0.14 m moves out of a 0.3 T field at 1.4 m/s along its longer side. How long does the emf last?