Question

The higher and lower fixed points on a thermometer are by 150mm. When the length of the Mercury thread above the lower temperature is 30 mm. The temperature reading would be

• A. 20C
• B. 30C
• C. 10C
• D. 0C

Answer 1

The correct option is A 20C

The temperature of the lower point is $0^{\circ }$ celcius $\left(0^{\circ }\right)$

That of upper point 100 degree celcius

so each of degree is represented by $\frac{150}{100}mm/degc=1.5mm/degc$

Therefore 30 mm of mercury

$=\frac{30}{1.5}={20}^{\circ }celcius$

Hence option (A) is correct