Thermal energy is incident on a surface at the rate of X J/min. If 'a' and 'r' represent the coefficients of absorption and reflection of the surface respectively, then the heat energy transmitted by the surface in 't' minutes is:

Which one of the following phenomena is primarily based on the process of convection?

The thermal resistance of a uniform conductor is:

Rods x and y of equal dimensions but of different materials are joined as shown in a linear arrangement (A-B-Junction-E-F). Temperatures of end points A and F are maintained at 100°C and 40°C respectively. Given that the thermal conductivity of rod x is three times that of rod y, and the center is split into parallel paths, the temperatures at junction points B and E are close to: