A light of wavelength \(\lambda \) is incident on the metal surface and the ejected fastest electron has speed \(v.\) If the wavelength is changed to \(\frac{3\lambda}{4},\) then the speed of the fastest emitted electron will be:

What did Einstein prove by the photo-electric effect?
1. \(E = h\nu\)
2. \(K.E = \frac{1}{2}mv^2\)
3. \(E= mc^2\)
4. \(E = \frac{-Rhc^2}{n^2}\)

The value of Planck's constant is:
1. \(6.63\times 10^{-34}~\text{J/s}\)
2. \(6.63\times 10^{-34}~\text{kg-}\text{m}^2\text{/s}\)
3. \(6.63\times 10^{-34}~\text{kg-}\text{m}^2\)
4. \(6.63\times 10^{-34}~\text{J-s}^2\)

According to Einstein's photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the frequency of incident radiation is:

1.		2.
3.		4.

The work functions for metals \(A,B,\) and \(C\) are respectively \(1.92\) eV, \(2.0\) eV, and \(5\) eV. According to Einstein's equation, the metals that will emit photoelectrons for a radiation of wavelength \(4100~\mathring{A}\) is/are:
1. None
2. \(A\) only
3. \(A\) and \(B\) only
4. All the three metals