MCQs of Dual Nature of Radiation and Matter

Dual Nature of Radiation and Matter MCQs

MCQs of Dual Nature of Radiation and Matter

Showing 161 to 170 out of 186 Questions

161.

Monochromatic light of frequency

f_{1}

irradiates a photo cell and stopping potential is found to be

V_{1}

. What is the new stopping potential of cell if it is irradiated by monochromatic light of frequency

f_{2}

(a)	$V_{1} + \frac{h}{e} (f_{2} - f_{1})$
(b)	$V_{1} - \frac{h}{e} (f_{2} - f_{1})$
(c)	$V_{1} - \frac{h}{e} (f_{2} + f_{1})$
(d)	$V_{1} - \frac{h}{e} (f_{1} + f_{2})$

162.

An ultraviolet light of wavelength 2000 Å irradiates a photo cell made of molybdenum metal. If the stopping potential is -1.5 V, what is the work function of metal ?

(a)	2.5×10^-19 J
(b)	5.0×10^-19 J
(c)	7.5×10^-19 J
(d)	1.0×10^-18 J

163.

Photo-electric emission is observed from a metallic surface for frequencies

f_{1}

and

f_{2}

of the incident light.

f_{1} > f_{2}

If the maximum values of K.E. of photo electrons emitted in two cases are in the ratio of 1:n, then the threshold frequency of a metallic surface is _____ .

(a)	$\frac{f_{1} - f_{2}}{(n - 1)}$
(b)	$\frac{{nf}_{1} - f_{2}}{n - 1}$
(c)	$ $\frac{{nf}_{2} - f_{1}}{(n - 1)}$ $
(d)	$\frac{f_{1} - f_{2}}{n}$

164.

Light of wavelength and photon energy 3 eV falling on a metal surface produces photo-electrons of maximum velocity v. If the wavelength of the incident light is changed to

\frac{3}{4} λ

and maximum velocity of the electron is doubled, the work function of the metal is nearly = _____ eV.

(a)	1.66
(b)	2.01
(c)	2.66
(d)	3.01

165.

The kinetic energy of photo-electron emitted from a metal are

K_{1}

and

K_{2}

when it is irradiated with lights of wavelength

λ_{1}

and

λ_{2}

respectively. The work function of metal is _____ .

(a)	$\frac{K_{1} λ_{1} - K_{2} λ_{2}}{λ_{2} - λ_{1}}$
(b)	$\frac{K_{1} λ_{1} + K_{2} λ_{2}}{λ_{2} + λ_{1}}$
(c)	$\frac{K_{1} λ_{2} + K_{2} λ_{1}}{λ_{2} - λ_{1}}$
(d)	$\frac{K_{1} λ_{2} + K_{2} λ_{1}}{λ_{2} + λ_{1}}$

166.

Threshold wavelength of tungsten is 2.73×10^-5 cm . Ultraviolet light of wavelength 1.8×10^-5 cm is incident on it, then maximum velocity of photo-electrons will be _____ ms^-1.

(a)	3.1×10⁵ cm
(b)	5.1×10⁵ cm
(c)	77.1×10⁵ cm
(d)	9.1×10⁵ cm

167.

Wavelength of light incident on a photo sensitive surface is reduced from 4000 Å to 360 nm. What will be the change in stopping potential ? n=6.625×10^-34 g.sec.

(a)	0.123 V
(b)	0.234 V
(c)	0.345 V
(d)	0.456 V

168.

2 mW light of wavelength 4400 Å is incident on photo sensitive surface of Cs. If quantum efficiency is 0.5 %, what will be the value of photoelectric current ?

(a)	1.56 μ A
(b)	2.56 μ A
(c)	4.56 μ A
(d)	3.54 μ A

169.

Compare the energy of photon of X-rays having wavelength 2 Å with the energy of electron having de Broglie wavelength 1 Å.

(a)	31.3
(b)	62.6
(c)	41.4
(d)	165.4

170.

An electron is at distance of 20 m from a point charge of 20 C. Its total energy is 15.6×10^-10 J . Find out the de Broglie wavelength of this point. h=6.6×10^-24 J.sec , m_e=9.1×10^-31 kg, k=9×10⁹ , e=1.6×10^-19 C

(a)	8.93×10^-15 m
(b)	9.93×10^-15 m
(c)	8.93×10^-14 m
(d)	8.93×10^-13 m

Showing 161 to 170 out of 186 Questions