Q.
The coefficient of volumetric expansion of mercury is 18×10−5/∘C. A thermometer bulb has value of 10−6m3 and crossectional of stem is 0.002cm2 assuming the bulb is tilled mercury at ∘C the length of mercury at 100∘C is:
The coefficient of volumetric expansion γ=18×10−5/∘C
Initial volume V=10−6m3
Area of cross section A=0.002cm2 =2×10−7m2
Initial temperature T1=0∘C
Final temperature T2=100∘C
The final volume is V=V[1+(T2−T2)] =10−6[1+18×10−5(100−0)]
and V=1.018×10−6
Change in volume is ΔV=A×Δl=V−V
or =2×10−7×Δl =1.018×10−6−106 2×10−7×Δl=0.018×10−6
Hence, Δl=2×10−70.018×10−6 =0.09m=9cm