Question

(1) Suppose the glass in thermometers had the same coefficient of expansion as the liquid in them. Would this affect the readings obtained with the thermometer? If so, how?

(2) Sometimes one observes that when a thermometer is plunged into a hot liquid, the thermometer reading drops for a brief instant before it begins to rise. Why might this happen?

(3) The thermal expansion formula is often written L = Lo (1 + α ΔT) Show that this form is consistent with equation 2.

Equation 2: α=(1/L)(dL/dT)

Answer 1

1. If the liquid inside the glass thermometer i e mercury and glass have smae co efficient of expansion..both glass and mercury will expand and contract at any given temperature. Thus the mercury will keep same relative height inside the tube.

2. The heat from fluid will first affect the glass making it expand and increase in volume. So the mercury will fill the increased volume in glass and when heat affects the mercury it begins to expand and fill the surface of thermometer

3.we can use equation 2 to find alpha value