Physics Test - ...

Consider a spherical shell of radius \(R\) at temperature \(T\). The black body radiation inside it can be considered as an ideal gas of photons with internal energy per unit volume \(u=\frac{U}{V} \alpha T^{4}\) and pressure \(P=\frac{1}{3}\left(\frac{U}{V}\right)\). If the shell now undergoes an adiabatic expansion the relation between \(T\) and \(R\) is:

A large cylindrical rod of length \(L\) is made by joining two identical rods of copper and steel of length \(\left(\frac{l}{2}\right)\) each.

The rods are completely insulated from the surroundings. If the free end of copper rod is maintained at \(100^{\circ} C\) and that of steel at \(0^{\circ} C\) then the temperature of junction is (Thermal conductivity of copper is 9 times that of steel)

The threshold frequency for a metallic surface corresponds to an energy of 6.2 eV and the stopping potential for a radiation incident on this surface is 5 V. The incident radiation lies in:

The maximum refractive index of a prism which permits the passage of light through it, when the refracting angle of the prism is \(90^{\circ}\), is:

A satellite is orbiting very close to planet.Its time period depends only upon _______.

The magnetic moment of an electron with orbital angular momentum \(\mathrm{J}\) will be :

The total energy of an electron in an atom inan orbit is –3.4 eV. Its kinetic and potentialenergies are, respectively :

A force (F) acting on a particle is such that F is inversely proportional to the distance covered. The work done by the force in moving the particle from point 'a' to point 'b' is proportional to: