What is the threshold frequency of a metal with a work function of $1.65 \ eV$?

The stopping potential for electrons emitted from a photosensitive surface illuminated by light of wavelength $491\, nm$ is $0.710\, V$. When the incident wavelength is changed to a new value,the stopping potential is $1.43\, V$. The new wavelength is ....... $nm.$

Light of wavelength $5000 \ \mathring A$ and intensity $4.68 \ mW/cm^2$ is incident on a photosensitive surface. If only $5\%$ of the incident photons produce photoelectrons,what is the number of photoelectrons emitted per unit area per unit time?

In a photoelectric experiment,the stopping potential was measured to be $V_1$ and $V_2$ volts with incident light of wavelength $\lambda$ and $\frac{\lambda}{2}$ respectively. The value of $V_2$ is: [where $\phi=$ work function,$e=$ electronic charge]

$A$ silver ball is suspended by a string in a vacuum chamber and ultraviolet light of wavelength $200 \ nm$ is incident on it. The maximum potential acquired by the ball,if the work function of silver is $4.7 \ eV$,will be .............. $V$.

$A$ point source of light is used in a photoelectric effect. If the source is moved farther from the emitting metal, the stopping potential: