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)
$5.2\times10^{-13}\, N$
$5.2\times10^{-12}\, N$
$5.22\times10^{-9}\, N$
zero
A radiation of energy $'E'$ falls normally on a perfectly reflecting surface. The momentum transferred to the surface is $( C =$ Velocity of light $)$
The energy equivalent to $1\,mg$ of matter in $MeV$ is
A photon collides with a stationary hydrogen atom in ground state inelastically. Energy of the colliding photon is $10.2 \ eV$. After a time interval of the order of micro second another photon collides with same hydrogen atom inelastically with an energy of $15 \ eV$. What will be observed by the detector
The momentum of the photon of wavelength $5000\,\mathring A$ will be
The number of photons emitted by a $10\,watt$ bulb in $10\,second,$ if wavelength of light is $1000\,\,\mathop A\limits^o ,$ is