The force between the plates of a parallel plate capacitor of capacitance '$$\mathrm{C}$$' and distance of separation of the plates '$$\mathrm{d}$$' with a potential difference '$$\mathrm{V}$$' between the plates is

Consider the following statements about stationary waves.

A. The distance between two adjacent nodes or antinodes is equal to $$\frac{\lambda}{2}(\lambda=$$ wavelength of the wave)

B. A node is always formed at the open end of the open organ pipe.

Choose the correct option from the following.

If the radius of the spherical gaussian surface is increased then the electric flux due to a point charge enclosed by the surface

The wave number of the last line of the Balmer series in hydrogen spectrum will be

(Rydberg's constant $$=10^7 \mathrm{~m}^{-1}$$ )