# A Capacitor with initial charge

## Homework Statement

A capacitor with initial charge q0 is discharged through a resistor. What multiple of the time constant τ gives the time the capacitor takes to lose

(a) the first 1/8-th of its charge
(b) 7/8-th of its charge?

## The Attempt at a Solution

since ı know q0.e-t/rc but ı could not do it

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berkeman
Mentor

## Homework Statement

A capacitor with initial charge q0 is discharged through a resistor. What multiple of the time constant τ gives the time the capacitor takes to lose

## Homework Equations

(a) the first 1/8-th of its charge
(b)7/8-th of its charge?

## The Attempt at a Solution

since ı know q0.e-t/rc but ı could not do it
Welcome to the PF.

Just set up those exponential equations and solve for time. Do you know how to take the natural log of both sides of an exponential equation to be able to pull the time variable out of the exponential?

Welcome to the PF.

Just set up those exponential equations and solve for time. Do you know how to take the natural log of both sides of an exponential equation to be able to pull the time variable out of the exponential?
no i dont know

berkeman
Mentor
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