Q112 / 125 · BITSAT 2019 · Physics

A charged capacitor of capacitance C is discharging through a resistor of resistance R. At what time the charge on the capacitor is equal to one half of its initial value?

  • A
    RC2
  • B
    RCloge2
  • Correct answer
    C
    RCloge 2
  • D
    1RCloge2

Solution

The charge on the capacitor at time t in a discharging circuit is given by q=q0e-t/τ

where, τ=RC= time constant
∴               q=q0e-t/RC

when,   q=q02

then  q02=q0e-t/RC

12=e-t/RC

Taking natural log on both side loge12=log0e-t/RC

-loge2=-tRClogee

⇒t=RCloge2

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

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