1. A certain metallic surface is illuminated with monochromatic light of wavelength, \(\lambda\). The stopping potential for photo-electric current for this light is \(3V_0\). If the same surface is illuminated with light of wavelength \(2\,\lambda\), the stopping potential is \(V_0\). The threshold wavelength for this surface for photo-electric effect is:

(1).\(6\,\lambda\)

(2). \(4\,\lambda\)

(3). \(\displaystyle \frac{\lambda}{4}\)

(4). \(\displaystyle \frac{\lambda}{6}\)

2. Which of the following options represent the variation of photoelectric current with property of light shown on x-axis?

(1).B and D

(2). A only

(3). A and C

(4). A and D

3. A photon and an electron (mass m) have the same energy E. The ratio(\(\lambda_\text{photon} / \lambda_\text{electron}\) ) of their de Broglie wavelengths is: (c is the speed of light)

(1).\(\displaystyle \frac{1}{\text{C}}\sqrt{\frac{\text{E}}{2\text{m}}}\)

(2). \(\displaystyle \sqrt{\frac{\text{E}}{2\text{m}}}\)

(3). \(\displaystyle \text{C}\sqrt{2\text{mE}}\)

(4). \(\displaystyle \text{C}\sqrt{\frac{2\text{m}}{\text{E}}}\)