NEET Electromagnetic Induction — Set 18

Question 1

A coil of 50 turns has an area of 0.03 m² in a 0.2 T field. If the field drops to zero in 0.1 s, what is the induced emf?

Accepted Answer

$ \Delta \Phi = B A = 0.2 \times 0.03 = 0.006 \, \text{Wb} $. $ \varepsilon = N \frac{\Delta \Phi}{\Delta t} = 50 \times \frac{0.006}{0.1} = 3 \, \text{V} $.

Question 2

A coil is placed near a current-carrying wire. If the current in the wire is suddenly switched off, what happens to the magnetic flux through the coil?

Accepted Answer

When the current is switched off, the magnetic field due to the wire collapses, reducing the magnetic flux through the coil from some value to zero.

Question 3

A rod rotates at 25 rad/s in a 0.3 T field. If the length from the axis to the tip is 0.8 m, what is the emf induced?

Accepted Answer

$ \varepsilon = \frac{1}{2} B \omega R^2 $. $ \varepsilon = \frac{1}{2} \times 0.3 \times 25 \times (0.8)^2 = 2.4 \, \text{V} $.

NEET Physics: Electromagnetic Induction — Practice Set 18

Q1. A coil of 50 turns has an area of 0.03 m² in a 0.2 T field. If the field drops to zero in 0.1 s, what is the induced emf?

Q2. A coil is placed near a current-carrying wire. If the current in the wire is suddenly switched off, what happens to the magnetic flux through the coil?

Q3. A rod rotates at 25 rad/s in a 0.3 T field. If the length from the axis to the tip is 0.8 m, what is the emf induced?

Q4. A rod of length 0.6 m moves at 2.5 m/s in a 0.25 T field perpendicular to its length. What is the induced emf?

Q5. A coil of 150 turns and area 0.01 m² is rotated at 40 Hz in a 0.06 T field. What is the maximum emf?

Q6. A coil of 200 turns is placed in a field that decreases from 0.05 T to 0 in 0.4 s. If the area is 0.02 m², what is the induced emf?

Q7. A solenoid of 600 turns and length 0.8 m induces an emf of 2 V in a nearby coil when its current changes from 1 A to 4 A in 0.2 s. What is the mutual inductance?

Q8. A conducting loop is twisted in a uniform magnetic field. The induced emf arises primarily from what change?

Q9. A wheel with 6 spokes of 0.6 m each rotates at 45 rpm in a 0.5 T field. What is the induced emf?

Q10. A loop of 0.3 m × 0.12 m moves out of a 0.4 T field at 2 m/s along its longer side. How long does the emf last?