- #1
SamS90
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Hello everyone, as you can tell I'm new and just wondering if I could get some help with this question as I'm not sure where exactly I've gone wrong:
Two wires are used to connect a lamp to a power supply of negligible internal resistance. The potential difference across the lamp is 12V and its power is 36W. Calculate the potential difference across each wire. The two wires in question are made of copper and have a resistivity of 1.7 x 10^-8 Ohm meter.
Not 100% sure but:
V=W/Q, R=V/I, I=P/V, E= I (R + r)
And I'm not sure about an others.
I = 36/12, I = 3
R = 12/3, R = 4
E = 3 (4 + 1.7x10^-8) = 12V
Therefore the potential difference across each wire is 12V
I know I've gone wrong some where and am hoping someone can put me right.
Many thanks,
Sam
Homework Statement
Two wires are used to connect a lamp to a power supply of negligible internal resistance. The potential difference across the lamp is 12V and its power is 36W. Calculate the potential difference across each wire. The two wires in question are made of copper and have a resistivity of 1.7 x 10^-8 Ohm meter.
Homework Equations
Not 100% sure but:
V=W/Q, R=V/I, I=P/V, E= I (R + r)
And I'm not sure about an others.
The Attempt at a Solution
I = 36/12, I = 3
R = 12/3, R = 4
E = 3 (4 + 1.7x10^-8) = 12V
Therefore the potential difference across each wire is 12V
I know I've gone wrong some where and am hoping someone can put me right.
Many thanks,
Sam