Unit IV: Electromagnetic Induction And Alternating Current - Online Test
Q1. An electron moves on a
straight line path XY as shown in the figure. The coil abcd is adjacent
to the path of the electron. What will be the direction of current, if any,
induced in the coil?
Answer : Option A
Explaination / Solution:
Q2.
A thin semi-circular conducting ring (PQR) of radius r is falling
with its plane vertical in a horizontal magnetic field B, as shown in the
figure.
Answer : Option D
Explaination / Solution:
Q3. The flux linked with a coil
at any instant t is given by ΦB = 10t 2 − 50t + 250. The induced emf at t = 3s is
Answer : Option B
Explaination / Solution:
Q4. When the current changes
from +2A to −2A in 0.05 s, an emf of 8 V is induced in a coil. The
co-efficient of self-induction of the coil is
Answer : Option D
Explaination / Solution:
Q5. The current i
flowing in a coil varies with time as shown in the figure. The variation of
induced emf with time would be
Answer : Option A
Explaination / Solution:
Q6. A circular coil with a
cross-sectional area of 4 cm2 has 10 turns. It is placed at the
centre of a long solenoid that has 15 turns/cm and a cross-sectional area of 10
cm2. The axis of the coil coincides with the axis of the solenoid.
What is their mutual inductance?
Answer : Option A
Explaination / Solution:
Q7. In a transformer, the number of turns in the primary and the secondary are 410 and 1230 respectively. If the current in primary is 6A, then that in the secondary coil is
Answer : Option A
Explaination / Solution:
Q8. A step-down transformer reduces the supply voltage from 220 V to 11 V and increase the current from 6 A to 100 A. Then its efficiency is
Answer : Option B
Explaination / Solution:
Q9. In an electrical circuit, R,
L, C and AC voltage source are all connected in series. When L is
removed from the circuit, the phase difference between the voltage and current
in the circuit is π /3 . Instead, if C is removed from the circuit,
the phase difference is again π / 3 . The power factor of the circuit is
Answer : Option C
Explaination / Solution:
Q10. In a series RL circuit, the resistance and inductive reactance are the same. Then the phase difference between the voltage and current in the circuit is
Answer : Option A
Explaination / Solution:
