The de-Broglie wavelength of an electron is the same as that of a photon of wavelength λ. If the mass of an electron is m, then its kinetic energy will be:

1.  $\frac{h^{2}m}{2{\lambda }^2}$

2.  $\frac{2h{m}^2}{{\lambda }^2}$

3.  $\frac{h^2{\lambda }^2}{2m}$

4.  $\frac{h^2}{2m{\lambda }^2}$

The variation of the kinetic energy \((K)\) of photoelectrons as a function of the frequency \((f)\) of the incident radiation is best shown by:

1.		2.
3.		4.

The correct graph between the maximum energy of a photoelectron \(\left(K_{max}\right)\) and the inverse of the wavelength \(\left(\frac{1}{\lambda}\right)\) of the incident radiation is given by the curve:

If alpha, beta and gamma rays carry the same momentum, which has the longest wavelength?

The photoelectric effect is used by a photocell to convert:

A 200 W sodium street lamp emits yellow light of wavelength 0.6 $\mathrm{\mu m}$. If it is 25% efficient in converting electrical energy to light, how many photons of yellow light does it emit per second?

1. $1.5\times {10}^{20}$

2. $6\times {10}^{18}$

3. $62\times {10}^{20}$

4. $3\times {10}^{19}$

In the photoelectric emission process from a metal of work function 1.8 eV, the kinetic energy of most energetic electrons is 0.5 eV. What is the corresponding stopping potential?

1. 1.3 V

2. 0.5 V

3. 2.3 V

4. 1.8 V

A source S₁ is producing, 10¹⁵ photons per sec of wavelength 5000 Å. Another source S₂ is producing 1.02×10¹⁵ photons per second of wavelength 5100 Å. Then the ratio of the power of S₂ to the power of S₁ is equal to:

Monochromatic light of frequency 6.0×10¹⁴ Hz is produced by a laser. The power emitted is 2×10^-3 W. What will be the average number of photons emitted by the source per second?

1. $5\times {10}^{15}$

2. $5\times {10}^{16}$

3. $5\times {10}^{17}$

4. $5\times {10}^{14}$