Question

When a current of (2.5 ± 0.5) A flows through a wire, it develops a potential difference of (20 ± 1) V. The resistance of wire is
(A) (8 ± 2) ohm (B) (8 ± 1.5) ohm
(C) (8 ± 0.5) ohm (D) (8 ± 3) ohm

Answer 1

Answer:

(B)......

Explanation:

option no.(B)

Answer 2

answer : option (A) (8 ± 2) Ω

explanation : applying Ohm's law, R = V/I

first find measured value of R and then deviation ∆R.

given, current = (2.5 ± 0.5)A and potential difference = (20 ± 1)V

measured value of resistance, R = V/I

so, R = 20/2.5 = 8Ω

now for finding deviation use formula,

∆R/R = ∆V/V + ∆I/I

or, ∆R/8 = 1/20 + 0.5/2.5

or, ∆R/8 = 0.05 + 0.2

or, ∆R = 8 × (0.25) = 2

hence, deviation in resistance, ∆R = 2Ω

so, resistance of wire is (8 ± 2)Ω

hence, option (A) is correct choice.