The spectrum obtained from an electric lamp or a red-hot heater is:

An electron moving with speed $v$ and a photon moving with speed $c$ have the same de Broglie wavelength. The ratio of the kinetic energy of the electron to that of the photon is -

When a monochromatic point source of light is placed at $0.1\, m$ from a photocell,the cut-off voltage and saturation current are $0.8\, V$ and $24\, mA$ respectively. If the same source is placed at $0.2\, m$ away from the photocell,then the cut-off voltage and saturation current will be:

Which of the following effects support the quantum nature of $EM$ radiation? $(1)$ Photoelectric effect $(2)$ Compton effect $(3)$ Doppler effect $(4)$ Field effect

An electron is moving through a field. It is moving $(i)$ opposite to an electric field and $(ii)$ perpendicular to a magnetic field as shown. For each situation,determine the de-Broglie wavelength of the electron.

The anode voltage of a photocell is kept fixed. The wavelength $\lambda$ of the light falling on the cathode is gradually changed. The plate current $I$ of the photocell varies as follows: