A radiation of energy $'E'$ falls normally on a perfectly reflecting surface. The momentum transferred to the surface is $( C =$ Velocity of light $)$
$\frac{E}{{C\;}}$
$\;\frac{{2E}}{C}$
$\;\frac{{2E}}{{{C^2}}}$
$\;\frac{E}{{{C^2}}}$
A $100 \;W$ sodium lamp radiates energy uniformly in all directions. The lamp is located at the centre of a large sphere that absorbs all the sodium light which is incident on it. The wavelength of the sodium light is $589\; nm$.
$(a)$ What is the energy per photon associated with the sodium light?
$(b)$ At what rate are the photons delivered to the sphere?
A radio transmitter radiates $1 kW$ power at a wavelength $198.6 $ metres. How many photons does it emit per second
A $5$ watt source emits monochromatic light of wavelength $5000\; \mathring A$. When placed $0.5\; m$ away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of $1.0\;m$, the number of photo electrons liberated will
There are materials which absorb photons of shorter wavelength and emit photons of longer wavelength. Can there be stable substances which absorb photons of larger wavelength and emit light of shorter wavelength.