Question

The resistance of wire is 5 ohm at 50C and 6 ohm at 100C. The resistance of the wire at 0C willbe

• A. 2 ohm
• B. 1 ohm
• C. 4 ohm
• D. 3 ohm

Answer 1

The correct option is C 4 ohm

Resistance of the wire must vary linearly with temperature.

Hence

$R=aT+b$ (let T be in degree scale)

Using $R\left(50\right)=5.$

$R\left(100\right)=6$

We get b = 4,

and $a=\frac{1}{50}$

Hence,

$R=\frac{T}{50}+4$

Putting R(0) for resistance at $0^{\circ }$ we get R(0) $=4$ ohm