There are two sources of light, each emitting with a power of $100 \,W.$ One emits $X-$ rays of wavelength $1\, nm$ and the other visible light at $500\, nm$. Find the ratio of number of photons of $X-$ rays to the photons of visible light of the given wavelength ? 

Vedclass pdf generator app on play store
Vedclass iOS app on app store

Power of radiation,

$\mathrm{P}=\frac{\mathrm{E}_{n}}{t}=\frac{n h f}{t}=\frac{n h c}{t \lambda}$

$\therefore \mathrm{P}=n^{\prime} \frac{h c}{\lambda} \quad$ (Where $n^{\prime}=$ no. of photons emitted per unit time)

$\therefore n^{\prime}=\left(\frac{\mathrm{P}}{h c}\right) \lambda$ $\therefore n^{\prime} \propto \lambda \quad(\because$ Here P, $h, c$ are constant $)$ $\therefore \frac{n_{1}^{\prime}}{n_{2}^{\prime}}=\frac{\lambda_{1}}{\lambda_{2}}$ $=\frac{1 \mathrm{~nm}}{500 \mathrm{~nm}}$ $\therefore \frac{n_{1}^{\prime}}{n_{2}^{\prime}}=\frac{1}{500}$

$\therefore\frac{n_{1}^{\prime}}{n_{2}^{\prime}}=\frac{\lambda_{1}}{\lambda_{2}}$

$=\frac{1 \mathrm{~nm}}{500 \mathrm{~nm}}$

$\therefore \frac{n_{1}^{\prime}}{n_{2}^{\prime}}=\frac{1}{500}$

Similar Questions

The work function of a photoelectric material is $3.3 eV$. The threshold frequency will be equal to

If the momentum of a photon is $p$, then its frequency is

Where $m$ is the rest mass of the photon

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

  • [IIT 2005]

A point source is emitting sound waves of intensity $16 \times 10^{-8} \mathrm{Wm}^{-2}$ at the origin. The difference in intensity (magnitude only) at two points located at a distances of $2 \mathrm{~m}$ and $4 \mathrm{~m}$ from the origin respectively will be______ $\times 10^{-8} \mathrm{Wm}^{-2}$

  • [JEE MAIN 2024]

A point source of light is placed at the centre of curvature of a hemispherical surface. The source emits a power of $24\,W$ The radius of curvature of hemisphere is $10\,cm$ and the inner surface is completely reflecting. The force on the hemisphere due to the light falling on it is $..........\times 10^{-8}\,N$.

  • [JEE MAIN 2023]