What is the stopping potential when a metal with a work function of $0.6 \ eV$ is illuminated with light of $2 \ eV$ (in $V$)?

The work function of a certain metal is $3.31 \times 10^{-19} \,J$. The maximum kinetic energy of photoelectrons emitted by incident radiation of wavelength $5000 \text{ Å}$ is (Given: $h = 6.62 \times 10^{-34} \,J \cdot s$,$c = 3 \times 10^8 \,m/s$,$e = 1.6 \times 10^{-19} \,C$) (in $\text{ eV}$)

An image of the sun is formed by a lens of focal length $30 \ cm$ on the metal surface of a photoelectric cell and a photoelectric current $I$ is produced. The lens forming the image is then replaced by another of the same diameter but of focal length $15 \ cm$. The photoelectric current in this case is

If the work function of a metal is $\phi$ and the frequency of the incident light is $v$,there is no emission of photoelectrons for:

If in a photoelectric experiment,the wavelength of incident radiation is reduced from $6000 \, \mathring{A}$ to $4000 \, \mathring{A}$,then:

The work function of a photosensitive metal surface is $\phi$. When a photon of energy $3\phi$ is incident on the surface,a photoelectron with a maximum velocity of $6.6 \times 10^6 \ m/s$ is emitted. If the energy of the incident photon is increased to $9\phi$,the maximum velocity of the emitted photoelectron will be ..........