In the Bohr atom, the number of de Broglie waves associated with the electron moving  in $n^{th}$ permitted orbit is

The wavelength of matter wave is independent of

An electron accelerated by a P.D. of V volts possesses a de Broglie wavelength $\lambda$. If the accelerating potential is increased by a factor of $4$, the de Broglie wavelength of the electron will

The relativistic expression for the wavelength of electrons moving with very high speed is