Rate of heat flow through two conducting rods of identical dimensions having thermal conductivities `K_(1)` and `K_(2)` and `Q_(1)` and `Q_(2)` when their ends are maintained at the same difference of temperature individually. When the two rods are joined in series with their ends maintained at the same temperature difference (as shown in the figure), the rate of heat flow will be

Options

A. `(Q_(1)+Q_(2))/(2)`
B. `(K_(1)Q_(2)+K_(2)Q_(1))/(K_(1)+K_(2))`
C. `(K_(1)Q_(1)+K_(2)Q_(2))/(K_(1)+K_(2))`
D. `(Q_(1)Q_(2))/(Q_(1)+Q_(2))`

Answer

D