A copper rod of 88 cm and an aluminium rod of unknown length have their increase in length independent of increase in temperature. The length of aluminium rod is `(alpha cu=1.7xx10^(-5) K^(-1) " and " alpha Al=2.2xx10^(-5) K^(-1))`

Options

A. 68cm
B. 6.8cm
C. 113.9cm
D. 88cm

Answer

A

Explanation

As per question, `Delta l_(Cu) = Delta l_(Al) or, l_(Cu) alpha_(Cu) Delta T= l_(Al) alpha_(Al) Delta T`
`l_(Al) = (l_(Cu) alpha_(Cu))/(alpha_(Al)) = (88 xx 1.7 xx 10^(-5))/(2.2 xx 10^(-5)) = 68cm`