Heat is passing from reservoir A to B through two rods of brass and iron of same length and area of cross-section. If K1 and K2 are the thermal conductivities of brass and iron, then equivalent thermal conductivity is given by
1
\(\rm \frac{2K_1K_2}{K_1+K_2}\)
2
\(\rm \frac{K_1+K_2}{K_1K_2}\)
3
K1 + K2
4
K1 .K2