Look at figure.

The length of wire PQ in case of A is equal to the diameter of the semicircle formed by the wire CDE

AcademicPhysicsNCERTClass 7

The length of the wire in $(A)$ is shorter than the wire in $(B)$. So, heat will reach to pin in $(A)$ fast and the wax will melt. So, pin in $(A)$ will fall first.

Updated on 10-Oct-2022 13:29:48