A certain metallic surface is illuminated with monochromatic light of wavelength \(\lambda\). The stopping potential for photoelectric 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 photoelectric effect's threshold wavelength for this surface is?
1. \(6\lambda\)
2. \(4\lambda\)
3. \(\dfrac{\lambda}{4}\)
4. \(\dfrac{\lambda}{6}\)

Which of the following figures represents the variation of the particle momentum and the associated de-Broglie wavelength?

1.		2.
3.		4.

What will be the percentage change in the de-Broglie wavelength of the particle if the kinetic energy of the particle is increased to \(16\) times its previous value?
1. \(25\)
2. \(75\)
3. \(60\)
4. \(50\)

For photoelectric emission from certain metal, the cut-off frequency is $\nu$. If radiation of frequency 2$\nu$ impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass)

1. $\sqrt{h\nu /\left(2m\right) }$

2. $\sqrt{h\nu /\left(m\right) }$

3. $\sqrt{2h\nu /\left(m\right) }$

4. none of these

A 200W sodium street lamp emits yellow light of wavelength $0.6 \mu m.$ Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is 

(1) $1.5\times {10}^{20}$                               

(2) $6\times {10}^{18}$

(3) $62\times {10}^{20}$                                 

(4) $3\times {10}^{19}$

Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V.The threshold frequency of the material is:

(1)$4\times {10}^{15}Hz$                               

(2)$5\times {10}^{15}Hz$

(3)$1.6\times {10}^{15}Hz$                           

(4)$2.5\times {10}^{15}Hz$