Question
Wed June 22, 2011 By:
 

A wire of 9 ohm resistance having 30 cm length is tripled on itself.what is the new resistance?

Expert Reply
Thu June 23, 2011
Given that: R = 9 ohm, l = 30 cm, Let the cross sectional area be A and specific resistance ?, then
 
R = ? l / A 
 
9 = ? x 30 / A
 
? / A = 3 / 10 ..................(1)
 
In new situation, let resistance = R', cross sectional area A' = 3 A and length l' = l/3 = 10 cm
 
So, R' = ? l' / A' = ? x 10 / 3 A = (3 / 10) x (10/3) = 1 ohm  
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