NEET Electromagnetic Induction — Set 9

Question 1

A rod of length 0.25 m moves at 3 m/s in a 0.4 T field perpendicular to its length. What is the induced emf?

Accepted Answer

$ \varepsilon = B l v = 0.4 \times 0.25 \times 3 = 0.3 \, \text{V} $.

Question 2

A conducting rod moves parallel to its length in a uniform magnetic field. Why is no emf induced across its ends?

Accepted Answer

Motional emf requires the rod to move perpendicular to the magnetic field to cut flux lines. Moving parallel to its length does not change the flux through any area, so no emf is induced.

Question 3

A coil of 120 turns and area 0.025 m² is in a field that decreases from 0.08 T to 0 in 0.4 s. What is the induced emf?

Accepted Answer

$ \Delta \Phi = B A = 0.08 \times 0.025 = 0.002 \, \text{Wb} $. $ \varepsilon = N \frac{\Delta \Phi}{\Delta t} = 120 \times \frac{0.002}{0.4} = 120 \times 0.005 = 0.6 \, \text{V} $.

NEET Physics: Electromagnetic Induction — Practice Set 9

Q1. A rod of length 0.25 m moves at 3 m/s in a 0.4 T field perpendicular to its length. What is the induced emf?

Q2. A conducting rod moves parallel to its length in a uniform magnetic field. Why is no emf induced across its ends?

Q3. A coil of 120 turns and area 0.025 m² is in a field that decreases from 0.08 T to 0 in 0.4 s. What is the induced emf?

Q4. A coil of 140 turns and area 0.05 m² is in a 0.1 T field that drops to zero in 0.25 s. What is the induced emf?

Q5. A bar magnet is pushed towards a coil with its north pole first, then pulled back. The direction of the induced current in the coil during withdrawal is opposite to that during approach due to what?

Q6. A loop moves into a 0.3 T field at 1 m/s. If the length perpendicular to velocity is 0.1 m, how long does the emf last?

Q7. A rectangular loop of 0.18 m × 0.3 m moves out of a 0.25 T field at 1 m/s along its shorter side. What is the emf?

Q8. In an AC generator, the frequency of the output voltage depends on which factor?

Q9. A coil is placed in a time-varying magnetic field. The direction of the induced current is determined by which principle?

Q10. A solenoid with mutual inductance 0.3 H has a current change of 6 A/s in the primary coil. What is the induced emf in the secondary coil?