A rod is measured using a scale. The reading is 60cm at 12∘C. If thermal coefficient of linear expansion of the rod is 3×10−5/∘C, the reading of the rod at 42∘C is:
(Assume the scale does not expand)
A
60.025cm
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B
60.054cm
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C
60.065cm
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D
59.985cm
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Solution
The correct option is B60.054cm The increment in length =αlΔT =3×10−5×60×(42−12) =3×10−5×60×30 =54×10−3cm =0.054cm
So, total length =(60+0.054)cm =60.054cm