A spherical black body with a radius of 12 cm radiates 450 watt power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be

Two identical bodies are made of a material for which the heat capacity increases with temperature. One of these is at 100^oC, while the other one is at 0^oC. If the two bodies are brought into contact, then, assuming no heat loss, the final common temperature is

Three liquids of densities $$\rho $$₁, $$\rho $$₂  and $$\rho $$₃ (with $$\rho $$₁ > $$\rho $$₂ > $$\rho $$₃), having the same value of surface tension T, rise to the same height in three identical capillaries. The angles of contact $$\theta $$₁, $$\theta $$₂ and $$\theta $$₃ obey

A rectangular film of liquid is extended from (4 cm $$ \times $$ 2 cm) to (5 cm $$ \times $$ 4 cm). If the work done is 3 $$ \times $$ 10^$$-$$4 J, the value of the surface tension of the liquid is