V/I: Power from Potential Difference & Current

[kara123]

Homework Statement

(a) Derive an expression for power in terms of potential difference and current.
(b) Use the result from part (a) and Ohm’s law to derive an expression for power in terms of current and resistance.

Relevant Equations

p= E/T
V=E/Q
I=Q/T

e=QxV
t=Q/I
p=(QxV)/(Q/I)
=V/I
The expression I came up with for a) is the potential difference divided by current to get power but I have no idea if that is even right if someone could just prompt me in the right direction that would be greatly appreciated

 

[hutchphd]

What is "e"? You mean" E"? And the algebra is incorrect in final step. But I like your approach.

 

[kara123]

yes i ment E

 

[BvU]

Hi,
Whatever you do, check the dimensions. Do you know how to do that ?
Basically your relevant equations:

[power] = [energy] per [time]
$\ \$[voltage] = [energy] per [charge]
[current] = [charge] per [time]​

For part b) you also need Ohm's law as a relevant equation !

$\$

 

[kuruman]

Check your algebra.
(QxV)/(Q/I) ≠ V/I

 

[kara123]

thankyou all for the help figured it out I must have been really tired while doing that algebra because I'm not sure what I was thinking the answer is P=VI