A steel wire of length L and diameter D has a resistance of

A steel wire, of length L and diameter D, has a resistance of 100 . What current would flow through a silver wire of the same diameter and the same length if a 20.0 V potential difference were applied across its length?

Express your answer in amperes to two significant figures.

THE ANSWER IS NOT .2!!

Solution

Here,

length of wire = L

diamtere = D

reistance , R = 100 Ohm

potential difference = 20 V

resistivity of silver , ps = 1.59 *10^-8 Ohm.m

resistivity of Steel , pA = 4.6 *10^-7 Ohm.m

Now , for the resistance of Silver

R = p * L/A

100 = 4.6 *10^-7 * L/A

L/A = 2.174 *10^8

Rs = ps * L/A

Rs = 2.174 *10^8 * 1.59 *10^-8

Rs = 3.45 Ohm

Now , using Ohm\'s law

I = V/Rs

I = 20/3.45 A

I = 5.79 A

the current I is 5.79 A