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## Homework Statement

1) a 12m length of wire with uniform cross sectional area 2.75x10^-7 has a potential difference of 15v applied across it, producing a current of 20A

a) find the resistivity of the wire B) what is the power dissipated in the wire?

2) 2 circuits are made. In circuit 1, 4 resistors (1,2,3,6 ohms) are connected in series. in circuit 2, the same 4 resistors are connected in parallel. The battery emf is 24 volts in both cases. Calculate the equivalent resistance of the each circuit and the current through each resistor.

3)http://img25.imageshack.us/my.php?image=46010928.png

determine the equivalent resistance and the total power deliverd by the battery for this ciruit.

Click here if you cant see the pic

http://img25.imageshack.us/my.php?image=46010928.png

## The Attempt at a Solution

1) a) r=I/V r=15/20 r=.75

b) p=IV p=20*15 p=300

2) Equivalent resistance for the series would be 12 because i just added the resistors up and i solved for current doing 24=I(12) V=IR so then the current through each resistor would be 2,4,6,12 respectively

for the parallel i did 1/rp=1/r1+1/r2+1/r3+1/r4 and got 1/3=rp, i solved current using v*r=I

24(1/3)=8 and then for each resistor the current was 24,12,8,4 respectively.

3) I am totally confused on this one?

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