Question
A capacitor is charged and then made to discharge through a resistance. The time constant is t. In what time will the potential difference across the capacitor decrease by 10 %?
τ ln 0.1
τ ln 0.9
τ ln
τ ln
Solution
C.
τ ln
As, we know that
q = q0 e-t/λ
According to the question
VC =
= e-t/λ
e-t/λ
et/λ =
⇒ t = τ ln