An electron and proton are separated by a large distance. The electron starts approaching the proton with energy $3\, {eV}$. The proton captures the electrons and forms a hydrogen atom in second excited state. The resulting photon is incident on a photosensitive metal of threshold wavelength $4000\, \mathring {{A}}$. What is the maximum kinetic energy of the emitted photoelectron ? (In ${eV}$)
$1.99$
$3.3$
$1.41$
$7.61$
A sensor is exposed for time $t$ to a lamp of power $P$ placed at a distance $l$. The sensor has a circular opening that is $4d$ in diameter. Assuming all energy of the lamp is given off as light, the number of photons entering the sensor if the wavelength of light is $\lambda $ is $(l >> d)$
Find the number of photons emitted per second by a $25$ watt source of monochromatic light of wavelength $6600 \mathring A$. What is the photoelectric current assuming $3 \%$ efficiency for photoelectric effect?
An electron and a photon each have a wavelength of $1.00\; nm$. Find
$(a)$ their momenta,
$(b)$ the energy of the photon, and
$(c)$ the kinetic energy of electron.
A photon, an electron and a uranium nucleus all have the same wavelength. The one with the most energy