In the two ‘set-ups’ X and Y, shown on the next page, the wires AB and PQR are made of the same material and have equal ‘thickness. The length of the wire AB, (in the set-up ‘X’) is equal to the diameter (= PR) of the semi-circle, formed by the wire PQR, (in the set-up ‘Y’). Pins, P1 and P2, are attached, to wires AB and PQR respectively, with the help of wax. Which of the two pins, P1 or P2, will fall off later? Give reason for your answer. (see figure in book)


Pin P2 will fall off later because length of the wire PQR is larger than that of wire AB. The required amount of heat to fall off the pins is received by the pin Pl first.