A brass rod and a lead rod each 80 cm long at `0^@C` are clamped together at one end with their free ends coinciding. The separatioin of free ends of the rods if the system is placed in a steam bath is (`alpha_("brass")=18xx10^(-6)//^(@)C` and `alpha_("lead")=28xx10^(-6)//^(@)C`)

Options

A. 0.2 mm
B. 0.8 mm
C. 1.4 mm
D. 1.6 mm

Answer

B

Explanation

`L_(2)-L_(1)=(L_(20)-L_(10))+(L_(2)alpha_(2)-L_(1)alpha_(1))DeltaT`
`L_(2)-L_(1)=0+(80xx28xx10^(-6)-80xx18xx10^(-6))100`
`=80xx10xx10^(-6)xx10^(2)=80xx10^(-3)`cm=0.8mm