When photons of energy $1 \ eV$ and $2.5 \ eV$ are incident on a metal surface with a work function of $0.5 \ eV$,what is the ratio of the maximum kinetic energies of the emitted photoelectrons?

When monochromatic light falls on a photo-sensitive metal,an electron is emitted with maximum velocity $1.6 \times 10^6 \ m/s$. Find the stopping potential.
[charge of electron $= 1.6 \times 10^{-19} \ C$,mass of electron $= 9 \times 10^{-31} \ kg$] (in $V$)

The electric field associated with a monochromatic light wave is given by $E = E_0 \sin \left[ \left( 1.57 \times 10^7 \text{ m}^{-1} \right) (x - ct) \right]$. The stopping potential when this light is used in a photoelectric experiment with a metal having a work function of $1.9 \text{ eV}$ is: (Planck's constant,$h = 6.64 \times 10^{-34} \text{ J-s}$) (in $\text{ V}$)

The threshold wavelength for the photoelectric effect on sodium is $5000 \ Å$. Its work function is:

The work function of a photosensitive material is $4.0 \ eV$. The longest wavelength of light that can cause photon emission from the substance is approximately $...... \ nm$.

When the wavelength of an incident photon is decreased, then: