InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
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. |
|
Answer» Given Resistance (R) = 2Ω Area of cross-section = A Length = l We know that R = \(ρ\frac{1}A\) ⇒ 2 = \(ρ\frac{1}A\) New Area = A/2 New Length = 2l New Resistance = R’ ⇒ R' = \(ρ\frac{2l}{\frac{A}{2}}\) ⇒ R' = \(ρ\frac{4l}{A}\) ⇒ R' = \(4ρ\frac{l}{A}\) ⇒ R' = 4 x 2 = 8, from (1) Hence the new resistance will be four times the previous resistance i.e. 8Ω. |
|