Question

The temperature coefficient of resistance of a coil of wire of resistance \(4 \Omega\) at \(30^\circ\text{C}\) and \(6 \Omega\) at \(70^\circ\text{C}\) (in per \(^\circ\text{C}\)) is

• A. 0.04
• B. 0.06
• C. 0.004
• D. 0.006
• E. 0.02

Hint:

If you use the approximate formula \(\alpha = \frac{R_2 - R_1}{R_1(t_2 - t_1)}\), you might get a slightly different value (\(2/160 = 0.0125\)). In competitive exams, always use the ratio method with \(R_0\) for more accuracy, or check which option matches your approximate result.

Answer 1

Answer: (E)