Question

A nichrome wire has resistance 20ohm.what will be the resistance of another nichrome wire whose length is greater by 5% and radius is greater by 1%?

Answer 1

Answer:

Given, resistance of first nichrome wire whose length is l and area of cross section is a is 10ohm

so, R = p×l/a = 10ohm ......(1)

now, for another nichrome wire

length L = 3l and A = 4a

so, R' = p× L/A

=> R' = p× 3l/4a

=> R' = 3/4 ( p×l/a)

=> R' = 3/4 R

=> R' = 3/4 × 10 ( from 1 )

=> R' = 7.5 ohm

hence, resistance of second nichrome wire is 7.5 ohm

Explanation: