The mass of a hydrogen molecule is 3.32 $$\times$$ 10^-27 kg. If 10²³ hydrogen molecules strike, per second, a fixed wall of area 2 cm² at an angle of 45^o to the normal, and rebound elastically with a speed of 10³ m/s, then the pressure on the wall is nearly:

The dipole moment of a circular loop carrying a current I, is m and the magnetic field at the centre of the loop is B₁. When the dipole moment is doubled by keeping the current constant, the magnetic field at the centre of the loop is $${{B_2}}$$. The ratio $${{{B_1}} \over {{B_2}}}$$ is:

An electron, a proton and an alpha particle having the same kinetic energy are moving in circular orbits of radii r_e, r_p, r$$_\alpha$$ respectively in a uniform magnetic field B. The relation between r_e, r_p, r$$_\alpha$$ is:

A granite rod of 60 cm length is clamped at its middle point and is set into longitudinal vibrations. The density of granite is 2.7 $$\times$$ 10³ kg/m³ and its Young’s modulus is 9.27 $$\times$$ 10¹⁰ Pa. What will be the fundamental frequency of the longitudinal vibrations ?