Q179 / 180 · KCET 2010 · Physics

A capacitor and an inductance coil are connected in separate AC circuits with a bulb glowing in both the circuits. The bulb glows more brightly when

  • A
    an iron rod is introduced into the inductance coil
  • B
    the number of turns in the inductance coil is increased
  • C
    separation between the plates of the capacitor is increased
  • Correct answer
    D
    a dielectric is introduced into the gap between the plates of the capacitor

Solution

Current, $\mathrm{i}=\frac{\mathrm{V}}{\sqrt{\mathrm{R}^{2}+\mathrm{X}_{\mathrm{C}}^{2}}}$ If a dielectric is introduced into the gap between the plates of capacitor. Its capacitance will increase and hence, impedance of the circuit will decrease. Thus, current and hence brightness of the bulb increase.

Hence, the correct answer is option: 'D'.

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