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Capacitance - urgent help please XD

2.0mF capacitor used as a backup power source. PD of 5.0V when fully charged.
Required to supply constant 1.0 microAmps and can be used until PD falls by 10%.
How long can it be used for?
Reply 1
V = Vnaught e^-t/rc

Use vnaught as 10% of v

rc we can calculate

use t = -(Ln(v/vnaught))RC
Reply 2
Original post by Kyx
V = Vnaught e^-t/rc

Use vnaught as 10% of v

rc we can calculate

use t = -(Ln(v/vnaught))RC

Thank you.
I thought of that but how can we work out RC if we don't have the resistance?
Reply 3
P = iv

p = v^2 / r

Original post by myabzz
thank you.
I thought of that but how can we work out rc if we don't have the resistance?
Reply 4
Original post by Kyx
P = iv

p = v^2 / r


Thank you, I think it is right
Reply 5
Original post by myabzz
Thank you, I think it is right


np

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