The spectrum of light emitted by a glowing solid is

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

Dual nature of light is exhibited by

Photoelectric effect experiments are performed using three different metal plates $p, q$ and $r$ having work functions $\phi_p=2.0 \ eV, \phi_q=2.5 \ eV$ and $\phi_r=3.0 \ eV$,respectively. $A$ light beam containing wavelengths of $550 \ nm, 450 \ nm$ and $350 \ nm$ with equal intensities illuminates each of the plates. The correct $I-V$ graph for the experiment is:

$A$ light beam of wavelength $500 \, nm$ is incident on a metal having a work function of $1.25 \, eV$,placed in a magnetic field of intensity $B$. The electrons emitted perpendicular to the magnetic field $B$,with maximum kinetic energy,are bent into a circular arc of radius $30 \, cm$. The value of $B$ is $.... \times 10^{-7} \, T$.
Given $hc = 20 \times 10^{-26} \, J \cdot m$,mass of electron $m_e = 9 \times 10^{-31} \, kg$,and $e = 1.6 \times 10^{-19} \, C$.