Question

The upper and lower fixed points of a thermometer are separated by 180 mm. What is the temperature in Celcius if the length of the mercury thread is 90 mm above the lower fixed point ?

• A. ${90}^{\circ }C$
• B. ${50}^{\circ }C$
• C. ${45}^{\circ }C$
• D. ${58}^{\circ }C$

Answer 1

The correct option is B ${50}^{\circ }C$

The upper and lower fixed points of a thermometer are separated by $180mm.$ Now the full scale is ${100}^{\circ }$C. If the mercury thread is at the point $X$ the temperature reading in the scale will be:
$t=\frac{90}{180}\times {100}^{o}C$.
So, the reading will be ${50}^{\circ }C$