The energy equivalent to $1\,mg$ of matter in $MeV$ is
$56.25 \times 10^{22}$
$56.25 \times 10^{24}$
$56.25 \times 10^{26}$
$56.25 \times 10^{28}$
Write charge on photon.
When radiation of wavelength $\lambda $ is incident on a metallic surface, the stopping potential is $4.8\, volts$. If the same surface is illuminated with radiation of double the wavelength, then the stopping potential becomes $1.6\, volts$. Then the threshold wavelength for the surface is
The force on a hemisphere of radius $1\, cm$ if a parallel beam of monochromatic light of wavelength $500\, nm$. falls on it with an intensity of $0.5\, W/cm^2$, striking the curved surface in a direction which is perpendicular to the flat face of the hemisphere is (assume the collisions to be perfectly inelastic)
The momentum of the photon of wavelength $5000\,\mathring A$ will be