# Three rods of Copper,

Question:

Three rods of Copper, Brass and Steel are welded together to form a Y-shaped structure. Area of cross-section of each rod $=4 \mathrm{~cm}^{2}$. End of copper rod is maintained at $100^{\circ} \mathrm{C}$ where as ends of brass and steel are kept at $0^{\circ} \mathrm{C}$. Lengths of the copper, brass and steel rods are 46,13 and $12 \mathrm{cms}$ respectively. The rods are thermally insulated from surroundings except at ends. Thermal conductivities of copper, brass and steel are $0.92,0.26$ and $0.12$ CGS units respectively. Rate of heat flow through copper rod is :

1. $4.8 \mathrm{cal} / \mathrm{s}$

2. $6.0 \mathrm{cal} / \mathrm{s}$

3. $1.2 \mathrm{cal} / \mathrm{s}$

4. $2.4 \mathrm{cal} / \mathrm{s}$

Correct Option: 1

Solution: