Question

*21. A brass meter bar is correct at 20°C. The length of a rod as measured by it at 35°C is
50cm. The true length of the rod at 35°C is
(coefficient of linear expansion of brass is
19 x 10-6rc).60
1) 40.01 m 2) 25.02 m 3)150.01 m 4)45.01 m​

Answer 1

Answer:

The answer should be 46dc - 5qc = b+4 dc

Explanation:

Answer 2

Answer:

The true length of the rod at  35°C is equal to 50.014cm.

Explanation:

Consider that $I_{1}$ is the actual length of the rod at 35°C.

Given, the measured length of the rod at 35°C,  $I_{2}=50cm$

Temperature at which brass meter bar is corrected = 20°C

Temperature at which rod is measured = 35°C

Temperature difference will be $dt=20-35=-15^{o}C$

Coefficient of linear expansion of brass, $\alpha =10*10^{-6}/^{o}C$

The brass meter bar is corrected at low temperature and measuring the rod at high temperature. Therefore, the actual length of the rod will be more than measured.

True length of the rod is given by:

$I_{1}=I_{2}[1-\alpha dt]$

$I_{1}=50cm[1-(19*10^{-6})(-15)]$

$I_{1}=50cm[1+0.000285]$

$I_{1}=50cm[1.0.000285]$

$I_{1}=50.014cm$

Therefore, the actual length of the rod is equal to 50.014cm.