Question

At 20 ◦C a copper wire has a resistance of 4×10−3 Ω and a temperature coefficient of resistivity of 3.9×10−3 (C◦)−1, its resistance at 100 ◦C is

A.
52.5 × 10-3 Ω
B.
5.25 × 10-3 Ω
C.
5.25 × 10-4 Ω
D.
5.25 × 10-2 Ω


E.
25.5 × 10-3 Ω

Answer 1

`R _(t) = R _(0)( \alpha t + 1) \\ = 4 * {10}^( - 3) (3.9 * {10}^( - 3) * 20 + 1) \\ = 4 * {10}^( - 3) (1.078) \\ = 4.312 * {10}^( - 3) \: Ω`