The value of threshold frequency depends on which of the following factors?

The number of photoelectrons emitted for light of a frequency $\nu$ (higher than the threshold frequency $\nu_0$) is proportional to

The work function of aluminium is $4.2 \ eV$. If two photons, each of energy $3.5 \ eV$, strike an electron of aluminium, then the emission of electrons will be:

In a photoelectric experiment,a parallel beam of monochromatic light with power of $200 \ W$ is incident on a perfectly absorbing cathode of work function $6.25 \ eV$. The frequency of light is just above the threshold frequency so that the photoelectrons are emitted with negligible kinetic energy. Assume that the photoelectron emission efficiency is $100 \%$. $A$ potential difference of $500 \ V$ is applied between the cathode and the anode. All the emitted electrons are incident normally on the anode and are absorbed. The anode experiences a force $F = n \times 10^{-4} \ N$ due to the impact of the electrons. The value of $n$ is. . . . .
Mass of the electron $m_e = 9 \times 10^{-31} \ kg$ and $1.0 \ eV = 1.6 \times 10^{-19} \ J$.

In the photoelectric effect,assuming the energy of a photon is proportional to its frequency and is completely absorbed by an electron in the metal,the photoelectric current...

The threshold frequency for a metal is $10^{15} \ Hz$. Choose the correct statement when light of wavelength $4000 \ \mathring A$ is incident on it.