# Need help capacitor discharge question

#### wertyu

Joined Jul 13, 2020
10
I got it wrong twice and i made a silly error now im on last chance to pass .

can someone check my answer and given advice for me , it would help a lot .

thanks

capacitor discharge

10v supply - total resistance in circuit 10.3 Kohms - 100microfarad capacitor .

need to find Volt and Current at 1 sec and 2 secs .

below is my work

Voltage = 10 x ( e -t/tc)

1 sec = 10 x 0.379 = 3.79v

2 sec = 10 x 0.14 = 1.4v

Current Io x (e-t/tc)

1 sec 0.00097 x 0.379 = 0.000367a

2 sec 0.00097 x 0.1437 = 0.000143a

#### Alec_t

Joined Sep 17, 2013
14,009
Welcome to AAC!
Re-check your equations for voltage and current. They are incorrect.
Show each stage of your working.

#### wertyu

Joined Jul 13, 2020
10
ok
time constant = 10300 ohms x 0.0001 microfarad = 1.03 secs

Voltage

1 sec 10V x e to the power of minus (1 / 1.03 ) 0.97 = 0.379 10 x 0.379 = 3.79V

2 sec 10V x e to the power of minus ( 2 / 1.03 ) 1.94 - = 0.14 10 x 0.14 = 1.4 V

Current

10 / 10300 = 0.00097 amp

0.00097 x e to the power of minus 1 / 1.03 0.97 = 0.379 = 0.00097 x 0.379 = 0.000367a 0.367ma

0.00097 x e to the power of minus 2 / 1.03 1.94 = 0.14 = 0.00097 x 0.14 = 0.00013 0.1ma

#### wertyu

Joined Jul 13, 2020
10
Welcome to AAC!
Re-check your equations for voltage and current. They are incorrect.
Show each stage of your working.
ok thanks done that

#### Alec_t

Joined Sep 17, 2013
14,009
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