According to Einstein's photoelectric equation,the graph between the kinetic energy of emitted photoelectrons and the frequency of incident radiation is:

$A$ stream of photons having energy $3 \,eV$ each impinges on a potassium surface. The work function of potassium is $2.3 \,eV$. The emerging photo-electrons are slowed down by a copper plate placed $5 \,mm$ away. If the potential difference between the two metal plates is $1 \,V$,the maximum distance the electrons can move away from the potassium surface before being turned back is .......... $mm$.

In the following diagram,if $V_2 > V_1$,then:

Photoelectrons are emitted when photons of energy $4.2 \text{ eV}$ are incident on a photosensitive metallic sphere of radius $10 \text{ cm}$ and work function $2.4 \text{ eV}$. The number of photoelectrons emitted before the emission is stopped is
$\left[\frac{1}{4 \pi \epsilon_0}=9 \times 10^9 \text{ SI unit; } e=1.6 \times 10^{-19} \text{ C}\right]$

$A$ certain metallic surface is illuminated by monochromatic radiation of wavelength $\lambda$. The stopping potential for photoelectric current for this radiation is $3V_{0}$. If the same surface is illuminated with a radiation of wavelength $2\lambda$,the stopping potential is $V_{0}$. The threshold wavelength of this surface for the photoelectric effect is $n\lambda$. Find the value of $n$.

The light rays having photons of energy $4.2\,eV$ are falling on a metal surface having a work function of $2.2\,eV$. The stopping potential of the surface is $.........\,V$.