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

When a photon of wavelength ${\lambda _1}$ is incident on a metal surface,the speed of the ejected fastest electron is $v_1 \ m/s$. If a photon of wavelength ${\lambda _2}$ is incident on the same metal,the speed of the ejected fastest electron is $v_2 \ m/s$. The value of $v_2^2 - v_1^2$ will be

The maximum wavelength of radiation that can produce the photoelectric effect in a certain metal is $200 \ nm$. The maximum kinetic energy acquired by an electron due to radiation of wavelength $100 \ nm$ will be .............. $eV$.

The threshold wavelength for photoelectric emission from a metal surface is $5200 \ \mathring A$. Which of the following sources will cause photoelectric emission from this surface?

In an experiment on the photoelectric effect,the slope of the cut-off voltage versus frequency of incident light is found to be $4.12 \times 10^{-15} \; V \cdot s$. Calculate the value of Planck's constant.

In an experiment to study the photoelectric effect,the observed variation of stopping potential $(V_0)$ with the frequency $(\nu)$ of incident radiation is as shown in the figure. The slope and $y$-intercept are respectively