Question

You measure the length of a brass rod on a hot July afternoon and a cool January evening, using the same aluminium scale. To your surprise, you find that the rod length is measured to be smaller on the summer day! How?

• A. Brass shrinks on heating
• B. Aluminium expands more on heating than brass
• C. Aluminium expands lesser than brass on heating
• D. None of these

Answer 1

The correct option is B Aluminium expands more on heating than brass

The scale has expanded during the summer day as compared to winter, along with the brass rod that you are measuring. The coefficient of linear expansion of aluminium is more than that of brass, hence the scale has expanded more than the rod - thus giving an apparent reading which is lesser than the true value.