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A coil of self-inductance L is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when:
A
an iron rod is inserted in the coil.
B
frequency of the AC source is decreased.
C
number of turns in the coil is reduced.
D
a capacitance of reactance $X_C = X_L$ is included in the same circuit.
Detailed Solution
Brightness decreases when an iron rod is inserted in the coil, as the inductance and hence the impedance of the circuit increases.
It increases when the frequency of the AC source is decreased, as the impedance decreases.
It increases when the number of turns in the coil is reduced, as the impedance decreases.
It increases when a capacitance of reactance $X_C = X_L$ is included, as the impedance decreases.
It increases when the frequency of the AC source is decreased, as the impedance decreases.
It increases when the number of turns in the coil is reduced, as the impedance decreases.
It increases when a capacitance of reactance $X_C = X_L$ is included, as the impedance decreases.