Question

In a resistance thermometer the resistances at $0^{\circ }C$ and ${100}^{\circ }C$ and 6.74 and 7.74 ohm respectively. The temperature corresponding to 6.53 ohm resistance is

• A. ${53}^{\circ }C$
• B. $-{21}^{\circ }C$
• C. $-{53}^{\circ }C$
• D. ${21}^{\circ }C$

Answer 1

The correct option is B $-{21}^{\circ }C$

For an interval of ${100}^{\circ }C$, change in resistance = 7.74 - 6.74 = 1 ohm.
For a change of 6.74 - 6.53 = 0.21 ohm, the change in temperature is $=\frac{100}{1.00}\times 0.21={21}^{\circ }C$. This corresponds to ${21}^{\circ }C$ less than $0^{\circ }C$.
Hence, the correct answer is option (b).