The wavelength λ_e of an electron and λ_p of a photon of same energy E are related by _____.

(a)

λ_p ∝ λ_e

(b)

\({ \lambda }_{ p }∝ \sqrt { { \lambda }_{ e } } \)

(c)

\({ \lambda }_{ p }∝ \frac { 1 }{ \sqrt { { \lambda }_{ e } } } \)

(d)

\({ \lambda }_{ p }∝ { \lambda }_{ e }^{ 2 }\)

In an electron microscope, the electrons are accelerated by a voltage of 14 kV. If the voltage is changed to 224 kV, then the de Broglie wavelength associated with the electrons would _____.

(a)

increase by 2 times

(b)

decrease by 2 times

(c)

decrease by 4 times

(d)

increase by 4 times

The wave associated with a moving particle of mass 3 x 10^–6 g has the same wavelength as an electron moving with a velocity 6 x 10⁶ ms^-1. The velocity of the particle is _____.

(a)

1.82 x 10^-18ms^-1

(b)

9 x 10^-2ms^-1

(c)

3 x 10^-31ms^-1

(d)

1.82 x 10^-15ms^-1

When a metallic surface is illuminated with radiation of wavelength λ, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2λ, the stopping potential is \(\frac{V}{4}\). The threshold wavelength for the metallic surface is _____.

(a)

4λ

(b)

5λ

(c)

\(\frac{5}{2}λ\)

(d)

3λ

If a light of wavelength 330 nm is incident on a metal with work function 3.55 eV, the electrons are emitted. Then the wavelength of the wave associated with the emitted electron is _____.(Take h = 6.6 x 10^–34 Js)

(a)

< 2.75 ×10⁻⁹m

(b)

≥ 2.75 × 10⁻⁹m

(c)

≤ 2.75 × 10⁻¹²m

(d)

< 2.5 × 10⁻¹⁰m

A photoelectric surface is illuminated successively by monochromatic light of wavelength λ and λ /2. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the material is _____.

(a)

\(\frac{hc}{\lambda}\)

(b)

\(\frac{2hc}{\lambda}\)

(c)

\(\frac{hc}{3\lambda}\)

(d)

\(\frac{hc}{2\lambda}\)

In photoelectric emission, a radiation whose frequency is 4 times threshold frequency of a certain metal is incident on the metal. Then the maximum possible velocity of the emitted electron will be _____.

(a)

\(\sqrt { \frac { { hv }_{ o } }{ m } } \)

(b)

\(\sqrt { \frac { { 6hv }_{ o } }{ m } } \)

(c)

\(2\sqrt { \frac { { hv }_{ o } }{ m } } \)

(d)

\(\sqrt { \frac { { hv }_{ o } }{2m } } \)

Two radiations with photon energies 0.9 eV and 3.3 eV respectively are falling on a metallic surface successively. If the work function of the metal is 0.6 eV, then the ratio of maximum speeds of emitted electrons in the two cases will be _____.

(a)

1:4

(b)

1:3

(c)

1:1

(d)

1:9

A light source of wavelength 520 nm emits 1.04 x 10¹⁵ photons per second while the second source of 460 nm produces 1.38 x 10¹⁵ photons per second. Then the ratio of power of second source to that of first source is _____.

(a)

1.00

(b)

1.02

(c)

1.5

(d)

0.98

If the mean wavelength of light from sun is taken as 550 nm and its mean power as 3.8 x 10²⁶ W, then the number of photons emitted per second from the sun is of the order of _____.

(a)

10⁴⁵

(b)

10⁴²

(c)

10⁵⁴

(d)

10⁵¹

The threshold wavelength for a metal surface whose photoelectric work function is 3.313 eV is _____.

(a)

4125 \(\mathring { A } \)

(b)

3750\(\mathring { A } \)

(c)

6000\(\mathring { A } \)

(d)

2062.5\(\mathring { A } \)

A light of wavelength 500 nm is incident on a sensitive metal plate of photoelectric work function 1.235 eV. The kinetic energy of the photoelectrons emitted is_____. (Take h = 6.6 x 10^–34 Js)

(a)

0.58 eV

(b)

2.48 eV

(c)

1.24 eV

(d)

1.16 eV

Photons of wavelength λ are incident on a metal. The most energetic electrons ejected from the metal are bent into a circular arc of radius R by a perpendicular magnetic field having magnitude B. The work function of the metal is _____.

(a)

\(\frac { hc }{ \lambda } -{ m }_{ e }+\frac { e^{ 2 }{ B }^{ 2 }{ R }^{ 2 } }{ { 2m }_{ e } } \)

(b)

\(\frac { hc }{ \lambda } +{ 2m }_{ e }{ \left[ \frac { eBR }{ { 2m }_{ e } } \right] }^{ 2 }\)

(c)

\(\\ \frac { hc }{ \lambda } -{ m }_{ e }{ c }^{ 2 }-\frac { e^{ 2 }{ B }^{ 2 }{ R }^{ 2 } }{ { 2m }_{ e } } \)

(d)

\(\frac { hc }{ \lambda } -{ 2m }_{ e }{ \left[ \frac { eBR }{ { 2m }_{ e } } \right] }^{ 2 }\)

The work functions for metals A, B and C are 1.92 eV, 2.0 eV and 5.0 eV respectively. The metal/metals which will emit photoelectrons for a radiation of wavelength 4100 Å is/are _____.

(a)

A only

(b)

both A and B

(c)

all these metals

(d)

none

Emission of electrons by the absorption of heat energy is called ______ emission.

(a)

photoelectric

(b)

field

(c)

thermionic

(d)

secondary