NEET Electromagnetic Induction — Set 7

Question 1

In an AC generator, the output voltage reverses direction every half-cycle due to what?

Accepted Answer

The coil’s rotation causes the flux to change sign every half-cycle as it passes from one field direction to the opposite, reversing the emf.

Question 2

A solenoid of 900 turns/m and area 0.018 m² has $ \mu_r = 1 $. What is its self-inductance? ($ \mu_0 = 4\pi \times 10^{-7} \, \text{H/m} $)

Accepted Answer

$ L = \mu_r \mu_0 n^2 A l $, assume $ l = 1 \, \text{m} $. $ L = 1 \times 4\pi \times 10^{-7} \times (900)^2 \times 0.018 \times 1 = 0.01831 \, \text{H} \approx 0.018 \, \text{H} $.

Question 3

A coil is placed in a magnetic field that oscillates rapidly. The induced emf is higher when what property of the field increases?

Accepted Answer

The induced emf depends on the rate of change of magnetic flux ($ \varepsilon = -\frac{d\Phi}{dt} $), which increases with the frequency of oscillation of the magnetic field.

NEET Physics: Electromagnetic Induction — Practice Set 7

Q1. In an AC generator, the output voltage reverses direction every half-cycle due to what?

Q2. A solenoid of 900 turns/m and area 0.018 m² has \( \mu_r = 1 \). What is its self-inductance? (\( \mu_0 = 4\pi \times 10^{-7} \, \text{H/m} \))

Q3. A coil is placed in a magnetic field that oscillates rapidly. The induced emf is higher when what property of the field increases?

Q4. A coil of 190 turns and area 0.03 m² is rotated at 40 Hz in a 0.09 T field. What is the maximum emf?

Q5. In an AC generator, increasing the number of turns in the coil affects what aspect of the output?

Q6. A wheel with 5 spokes of 0.65 m each rotates at 42 rpm in a 0.7 T field. What is the induced emf?

Q7. A rod of length 0.35 m moves at 2.5 m/s in a 0.2 T field perpendicular to its length. What is the induced emf?

Q8. A circular loop of radius 17 cm is deformed into a straight wire in a 0.15 T field in 0.5 s. What is the induced emf?

Q9. A rod rotates at 30 rad/s in a 0.6 T field. If the length from the axis to the tip is 0.8 m, what is the emf induced?

Q10. Two nearby coils are arranged such that a changing current in one induces an emf in the other. The strength of this effect is quantified by what property?