Question

The smallest temperature difference measured with a thermocouple of e.m.f. $30\,\mu VC^{-1}$ and a galvanometer of $50 \,\Omega$ and capable of measuring a minimum current of $3 \times 10^{-7}$ is

• A. 0.5 $^\circ$
• B. 1$^\circ$
• C. 1.5$^\circ$
• D. 2$^\circ$

Answer 1

Answer: (A)

Using V = 1R we get V = $3 \times 10^{-7} \times 50$
Detectable temperature difference = $\frac{V}{E} = \frac{3 \times 10^{-7} \times 50}{30 \times 10^{-6}} = 0.5^\circ$