Question

a length of wire has a resistance of 2.5ohm. find the resistance of another wire of same material twice in length and 5 times big cross sectional area​

Answer 1

Explanation:

Resistance (R) = 2Ω Area of cross-section = A Length = l We know that R = ρ1Aρ1A ⇒ 2 = ρ1Aρ1A New Area = A/2 New Length = 2l New Resistance = R’ ⇒ R' = ρ2lA2ρ2lA2 ⇒ R' = ρ4lAρ4lA ⇒ R' = 4ρlA4ρlA ⇒ R' = 4 x 2 = 8, from (1) Hence the new resistance will be four times the previous resistance i.e. 8Ω.Read more on Sarthaks.com - https://www.sarthaks.com/956888/a-wire-of-given-material-having-length-l-and-area-of-cross-section-a-has-a-resistance-of-2

Answer 2

Answer in full solution