Two sphere of same material have radii 1 m & 4 m and temperatures 4000 k & 2000 k respectivel. Find the ratio of the energy radiated per second by the first sphere to that by the second.

State Stefan’s Law. The radii of two spheres are 1 m and 4 m and temperatuiie 4000 K and 2000 K respectively. Calculate the ratio of the energy radiated per second.

Two black bodies A and B have equal surface areas and are maintained at temperatures 27° C and 177° C respectively. What will be the ratio of the thermal energy radiated per second by A to that by B ?

Two wires of the same length but of difference materials have diameter of 1mm and 3mm respectively.IF both of them are stretched by the same force,then the elongation of the first wire becomes thrice that of the second. Compare their Young's modull.

Two wires A and B of same material have radii in the ratio 2 : 1 and lengths in the ratio 4 : 1. The ratio of the normal forces required to produce the same change in the lengths of these two wires is

Two spheres of radii 4 cm and 8 cm have the same amount of charge. Determine the ratio of their surface densities of charge.

If the ratio of the radii of two spheres be 1 : 2, then find the ratio of their curved surfac areas.