Question

The coefficient of volumetric expansion of mercury is 18×10^-5/°C. The thermometer bulb has a volume of 10^-6 m^3 and cross-section of the stem is 0.002cm^2. Assuming that bulb is filled with mercury at 0°C, the increase in length of the mercury column at 100°C will be ___________

(a) 9cm

(b) 9mm

(c) 18cm

(d) 18mm

The question was posed to me in a job interview.

Question is from Absorption and Emission topic in section Kinetic Theory of Gases of Engineering Physics I

Answer 1

Right answer is (a) 9cm

To explain: Let h be the length of mercury column at 100°C. Then

Expansion in mercury = Volume of stem

γV∆T=Ah

h=γV∆T/A=(18×10^-5×10^-6×100)/(0.002×10^-4) m

h=9×10^-2 m

h=9cm.