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______ $\times 10^{-8} \mathrm{Wm}^{-2}$
$3$
$2$
$1$
$5$
The frequency of a photon, having energy $100eV$ is$(h = 6.6\,{10^{ - 34}}\,J{\rm{ - }}sec)$
Photon and electron are given same energy $({10^{ - 20}}J)$. Wavelength associated with photon and electron are ${\lambda _{Ph}}$ and ${\lambda _{el}}$ then correct statement will be
The momentum of a photon with energy $20\, eV$ is
The work functions of Caesium $(Cs)$,Potassium $(K)$ and Sodium $(Na)$ are $2.14\,eV,2.30\,eV$ and $2.75\,eV$ respectively. If incident electromagnetic radiation has an incident energy of $2.20\, eV$, which of these photosensitive surfaces may emit photoelectrons?