When a monochromatic point source of light is at a distance of $0.2\, m$ from a photoelectric cell,the cut-off voltage and the saturation current are respectively $0.6\, V$ and $18.0\, mA$. If the same source is placed $0.6\, m$ away from the photoelectric cell,then

The graph shows the variation of photocurrent with anode potential for four different radiations. Let $I_a, I_b, I_c$ and $I_d$ be the intensities and $f_a, f_b, f_c$ and $f_d$ be the frequencies for the curves $a, b, c$ and $d$ respectively,then

For photoelectric emission, tungsten requires light of $2300 \mathring{A}$. If light of $1800 \mathring{A}$ wavelength is incident, then emission:

Describe Hallwach's and Lenard's observations regarding the photoelectric effect in short.

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 $1.0 \ eV = 1.6 \times 10^{-19} \ J$.

When yellow light is incident on a surface,no electrons are emitted,while green light can emit them. If red light is incident on the surface,then: