Question

A semicircular metal ring subtends an angle of ${180}^0$ at the center of the circle. When it is heated, this angle

• A. remains constant.
• B. increases slightly.
• C. decreases slightly.
• D. becomes ${360}^0$.

Answer 1

Answer: (A)

remains constant.

When the semicircular metal ring is heated, it expands outwardly. The hole inside it also expands in the same ratio. Hence the angle at the centre remains the same i.e. 180 degree.