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Calculate charge when given power, resistance and time

Question: power is 15. resistance is 5 ohms.Time is one minute. calculate charge.

would you use P = I squared x R?
the answer is 103 to 1dp



P = 15

R = 5

T = 1



The formula for charge flow is Q=IT



So you have to rearrange P= I squared R



And when you rearrange you get square root 15/3



Then you multiply it by 60 because the time is supposed to be in seconds. and then you get the anser 103.9230485


hope it helps :smile:
Reply 2
Original post by rockyball89
the answer is 103 to 1dp

P = 15

R = 5

T = 1



The formula for charge flow is Q=IT



So you have to rearrange P= I squared R



And when you rearrange you get square root 15/3



Then you multiply it by 60 because the time is supposed to be in seconds. and then you get the anser 103.9230485


hope it helps :smile:



how did you go from q= it to p = i squared R
you have to rearrange it since you need the (I) to get the charge flow.

So the formula is P =I2r

If you put it in a triangle it would be

P

I2 x R

And since you want the "I" you cover it and that would mean I = P x R. However, the I has a squared in front of it, so you must do the opposite and square root it. So it would be Square root P/R

Hope that helps :smile: Anymore questions feel free to let me know
Reply 4
Original post by qwertyK
how did you go from q= it to p = i squared R

V = IR

P = IV
P = I (IR)
P = I squared x R
Making I the subject of the formula, I = square root of P/R

Q = It
Q = (square root of P/R) x t

I hope it helped!
(edited 2 months ago)

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