A wire of given material having length l and area of cross-section A, has a resistance of 2 Ω. Find the resistance of another wire of same material having length 2l and are of cross-section A/2.
Given
Resistance (R) = 2Ω
Area of cross-section = A
Length = l
We know that
⇒ (1)
New Area = A/2
New Length = 2l
New Resistance = R’
⇒
⇒
⇒
⇒ from (1).
Hence the new resistance will be four times the previous resistance i.e. 8Ω.