Two spherical black bodies of radii `R_(1)` and `R_(2)` and with surface temperature `T_(1)` and `T_(2)` respectively radiate the same power. `R_(1)//R_(2)` must be equal to

Two spherical black bodies of radii r_(1) and r_(2) and with surface temperatures T_(1) and T_(2) respectively, radiate the same power. Then r_(1)//r_(2) must be equal to

Figure shows a system of two concentric spheres of radii r_(1)" and "r_(2) at the temperatures T_(1)" and "T_(2) , respectively. The radial rate of flow of heat in a substance filled between the two concentric spheres is proportional to

A and B are two satellite revolving around the earth in circular orbits with radii R_(A) and R_(B) . Their periods T_(A) and T_(B) are 8 h and 1 h respectively. Then the ratio of (R_(A)//R_(B)) is equal to

Two charged spherical conductors of radii R_(1) and R_(2) are connected by a wire. Then the ratio of surface charge densitites of the spheres sigma_(1)//sigma_(2) is

The figure shows a system of two concentric spheres of radii r_1 and r_2 are kept at temperature T_1 and T_2 , respectively. The radial rate of flow of heat in a substance between the two concentric spheres is proportional to