NEET | 2013Current Electricity and Electrical InstrumentHard
Question
A coil is self-inductance L is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when :
Options
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 XC = XL is included in the same circuit.
Solution
Brightness of the bulb
• decreases when an iron rod is inserted in the coil as impedance of circuit increases.
• increases when frequency of the AC source is decreased as impedance of circuit decreases.
• Increases when number of turns in the coil is reduced as impedance of circuit decreases.
• increases when a capacitance of reactance XC = XL is included in the circuit as impedance of circuit decreases.
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