An electron microscope uses electrons of $40 \ keV$. The de Broglie wavelength associated with these electrons is approximately:

Consider an electron $(m = 9.1 \times 10^{-31} \ kg)$ confined by electrical forces to move between two rigid walls separated by $1.0 \times 10^{-9} \ m$,which is about five atomic diameters. The quantized energy value for the lowest stationary state is

Electrons used in an electron microscope are accelerated by a voltage of $25 \; kV$. If the voltage is increased to $100 \; kV$,then the de-Broglie wavelength associated with the electrons would

An $\alpha$-particle moves in a circular path of radius $1 \ cm$ in a uniform magnetic field of $0.125 \ T$. The de Broglie wavelength associated with the $\alpha$-particle is

An electron is released from rest near an infinite non-conducting sheet of uniform charge density $-\sigma$. The rate of change of de Broglie wavelength associated with the electron varies inversely as the $n^{\text{th}}$ power of time. The numerical value of $n$ is . . . . . . .

The de-Broglie wavelength $\lambda$ of a particle is: