- #1

Googl

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## Homework Statement

I have managed to calculate the first part of the question but the second part b I keep getting wrong. I was wondering whether you might give me some guidance. I am trying to find the current after 50s in part b below.

## Homework Equations

time constant = RC

## The Attempt at a Solution

**a)**Time constant = RC = (50 x 10-6 F) x (100, 000Ω)

Time constant = (5 x 10-5 F) x (100, 000Ω)

Time constant = 5s

**Correct**

**b)**T1/2 = 5 x In 2 = 3.4657...

50 seconds corresponds to 50/3.4657 = 14.41 half-times.

Δ changing current 14.41t1/2 = 90µA/2^14.41 = 4.13 x 10^-3 µA = 4.13 x 10^-6A

Current after 50 seconds is 4.13 x 10^-6A

This is wrong. Help. Thanks.