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A coil of self-inductance is connected in series with a bulb and an AC source. Brightness of the bulb decreases when:

  1. A
    frequency of the AC source is decreased
  2. B
    number of turns in the coil is reduced
  3. C
    a capacitance of reactance is included
  4. D
    an iron rod is inserted in the coil

Solution & Step-by-step Explanation

image
Brightness depends on the current .Inserting an iron rod increases the permeability , which increases ().Higher leads to higher inductive reactance .This increases the impedance , thereby decreasing the current and the brightness.

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A coil of self-inductance is connected in series with a bulb and an AC source. Brightness of the bulb decreases when:
A
frequency of the AC source is decreased
B
number of turns in the coil is reduced
C
a capacitance of reactance is included
D
an iron rod is inserted in the coil

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