Question 1: Palette 1/87

NEET 2026 MCQ

$ \text { Match List I with List II. } $

$ \text { List-I } $		$ \text { List-II } $
A.	$E=h v$	I.	de Broglie wavelength
B.	Diffraction and Interference	II.	Particle nature of light
C.	$\lambda=h / p$	III.	Wave nature of light
D.	Compton effect	IV.	Energy of photon

A

A-IV, B-I, C-II, D-III

B

A-IV, B-III, C-II, D-I

C

A-I, B-IV, C-III, D-II

D

A-IV, B-III, C-I, D-II

Question 2: Palette 2/87

NEET 2026 MCQ

For a metal of work function 6.6 eV , which of the following wavelengths of incident radiation does not give rise to the photoelectric effect?

(Take Planck's constant as $6.6 \times 10^{-34} \mathrm{~J} \mathrm{~s}$ )

A

100 nm

B

150 nm

C

200 nm

D

50 nm

Question 3: Palette 3/87

NEET 2026 MCQ

A photon and an electron, each of 20 eV energy, move in free space. The ratio of linear momentum of electron $\mathrm{p}_{\mathrm{e}}$ to that of photon $\mathrm{p}_{\mathrm{Ph}}, \frac{\mathrm{p}_{\mathrm{e}}}{\mathrm{p}_{\mathrm{Ph}}}$ is:

[Take speed of light $=3 \times 10^8 \mathrm{~ms}^{-1}$, charge of electron $=-1.6 \times 10^{-19} \mathrm{C}$ and mass of electron $=9 \times 10^{-31} \mathrm{~kg}$ ]

A

275

B

$\frac{2}{450}$

C

$\frac{1}{250}$

D

225

Question 4: Palette 4/87

NEET 2026 MCQ

A beam of light falls on a metal surface such that photo-electrons are generated. If power of the light source starts to decrease linearly with time $t$, then variation of the photocurrent $I$ and magnitude of the stopping potential $|V|$ with time is best represented by:

A

B

C

D

Question 5: Palette 5/87

NEET 2026 MCQ

A ray of light with wavelength $\lambda$ is incident on three different photoelectric cells namely 1,2 and 3 . The threshold wavelength of these photoelectric cells are $\lambda_1, \lambda_2$, and $\lambda_3$, respectively and the magnitude of stopping potentials of these cells are $V_1, V_2$ and $V_3$, respectively. The relation between $\lambda$ and threshold wavelengths are $\lambda_1<\lambda, \lambda_2>\lambda$ and $\lambda_3 \gg \lambda$. The correct option is:

A

$V_1< V_2, V_3=0$

B

$V_1=0, V_2< V_3$

C

$V_1=0, V_2>V_3$

D

$V_1>V_2, V_3=0$

Question 6: Palette 6/87

NEET 2025 MCQ

De-Broglie wavelength of an electron orbiting in the $n=2$ state of hydrogen atom is close to

(Given Bohr radius $=0.052 \mathrm{~nm}$ )

A

1.67 nm

B

2.67 nm

C

0.067 nm

D

0.67 nm

Question 7: Palette 7/87

NEET 2025 MCQ

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

A

A and D

B

B and D

C

A only

D

A and C

Question 8: Palette 8/87

NEET 2025 MCQ

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)

A

$c \sqrt{\frac{2 m}{E}}$

B

$\frac{1}{c} \sqrt{E / 2 m}$

C

$\sqrt{E / 2 m}$

D

$c \sqrt{2 m E}$

Question 9: Palette 9/87

NEET 2024 MCQ

An electron and an alpha particle are accelerated by the same potential difference. Let $\lambda_e$ and $\lambda_\alpha$ denote the de-Broglie wavelengths of the electron and the alpha particle, respectively, then:

A

$\lambda_e>\lambda_\alpha$

B

$\lambda_e=4 \lambda_\alpha$

C

$\lambda_e=\lambda_\alpha$

D

$\lambda_e<\lambda_\alpha$

Question 10: Palette 10/87

NEET 2024 MCQ

If $\phi$ is the work function of photosensitive material in $\mathrm{eV}$ and light of wavelength of numerical value $\lambda=\frac{h c}{e}$ metre, is incident on it with energy above its threshold value at an instant then the maximum kinetic energy of the photo-electron ejected by it at that instant (Take $h$-Plank's constant, $c$-velocity of light in free space) is (in SI units):

A

$e+2 \phi$

B

$2 e-\phi$

C

$e-\phi$

D

$e+\phi$

Question 11: Palette 11/87

NEET 2024 MCQ

The graph which shows the variation of $\left(\frac{1}{\lambda^2}\right)$ and its kinetic energy, $E$ is (where $\lambda$ is de Broglie wavelength of a free particle):

A

B

C

D

Question 12: Palette 12/87

NEET 2024 MCQ

If $c$ is the velocity of light in free space, the correct statements about photon among the following are:

A. The energy of a photon is $E=h v$.

B. The velocity of a photon is $c$.

C. The momentum of a photon, $p=\frac{h v}{c}$.

D. In a photon-electron collision, both total energy and total momentum are conserved.

E. Photon possesses positive charge.

Choose the correct answer from the options given below:

A

A and B only

B

A, B, C and D only

C

A, C and D only

D

A, B, D and E only

Question 13: Palette 13/87

NEET 2023 MCQ

The de Broglie wavelength associated with an electron, accelerated by a potential difference of 81 V is given by:

A

13.6 nm

B

136 nm

C

1.36 nm

D

0.136 nm

Question 14: Palette 14/87

NEET 2023 MCQ

The maximum kinetic energy of the emitted photoelectrons in photoelectric effect is independent of:

A

work function of material

B

intensity of incident radiation

C

frequency of incident radiation

D

wavelength of incident radiation

Question 15: Palette 15/87

NEET 2023 MCQ

The work functions of Caesium $(\mathrm{Cs})$, potassium $(\mathrm{K})$ and Sodium (Na) are $2.14 ~\mathrm{eV}, 2.30 ~\mathrm{eV}$ and $2.75 ~\mathrm{eV}$ respectively. If incident electromagnetic radiation has an incident energy of $2.20 ~\mathrm{eV}$, which of these photosensitive surfaces may emit photoelectrons?

A

Both Na and K

B

K only

C

Na only

D

Cs only

Question 16: Palette 16/87

NEET 2023 MCQ

The minimum wavelength of $X$-rays produced by an electron accelerated through a potential difference of $V$ volts is proportional to :

A

$\frac{1}{V}$

B

$\frac{1}{\sqrt{V}}$

C

$V^{2}$

D

$\sqrt{V}$

Question 17: Palette 17/87

NEET 2022 MCQ

The light rays having photons of energy 4.2 eV are falling on a metal surface having a work function of 2.2 eV. The stopping potential of the surface is

A

6.4 V

B

2 eV

C

2 V

D

1.1 V

Question 18: Palette 18/87

NEET 2022 MCQ

The threshold frequency of a photoelectric metal is v₀. If light of frequency 4v₀ is incident on this metal, then the maximum kinetic energy of emitted electrons will be :

A

4 hv₀

B

hv₀

C

2 hv₀

D

3 hv₀

Question 19: Palette 19/87

NEET 2022 MCQ

When two monochromatic lights of frequency, v and ${v \over 2}$ are incident on a photoelectric metal, their stopping potential becomes ${{{V_s}} \over 2}$ and V_s respectively. The threshold frequency for this metal is

A

2v

B

3v

C

${2 \over 3}$v

D

${3 \over 2}$v

Question 20: Palette 20/87

NEET 2021 MCQ

The number of photons per second on an average emitted by the source of monochromatic light of wavelength 600nm, when it delivers the power of 3.3 $\times$ 10^$-$3 watt will be : (h = 6.6 $\times$ 10^$-$34 Js)

A

10¹⁵

B

10¹⁸

C

10¹⁷

D

10¹⁶

Question 21: Palette 21/87

NEET 2021 MCQ

An electromagnetic wave of wavelength '$\lambda$' is incident on a photosensitive surface of negligible work function. If 'm' mass is of photoelectron emitted from the surface has de-Broglie wavelength $\lambda$_d, then :

A

$\lambda = \left( {{{2h} \over {mc}}} \right){\lambda _d}^2$

B

$\lambda = \left( {{{2m} \over {hc}}} \right){\lambda _d}^2$

C

${\lambda _d} = \left( {{{2mc} \over h}} \right){\lambda ^2}$

D

$\lambda = \left( {{{2mc} \over h}} \right){\lambda _d}^2$

Question 22: Palette 22/87

NEET 2020 MCQ

Light of frequency 1.5 times the threshold frequency is incident on a photosensitive material. What will be the photoelectric current if the frequency is halved and intensity is doubled?

A

four times

B

one-fourth

C

zero

D

doubled

Question 23: Palette 23/87

NEET 2020 MCQ

Light with an average flux of 20 W/cm² falls on a non-reflecting surface at normal incidence having surface area 20 cm². The energy received by the surface during time span of 1 minute is :

A

12 $ \times $ 10³ J

B

24 $ \times $ 10³ J

C

48 $ \times $ 10³ J

D

10 $ \times $ 10³ J

Question 24: Palette 24/87

NEET 2020 MCQ

An electron is accelerated from rest through a potential difference of V volt. If the de-Broglie wavelength of the electron is 1.227 $ \times $ 10^-2 nm, the potential difference is :

A

10² V

B

10³ V

C

10⁴ V

D

10 V

Question 25: Palette 25/87

NEET 2019 MCQ

An electron is accelerated through a potential difference of 10,000 V. Its de Broglie wavelength is (nearly) : (m_e = 9 $ \times $ 10^–31 kg)

A

12.2 × 10^–12 m

B

12.2 × 10^–13 m

C

12.2 × 10^–14 m

D

12.2 nm

Question 26: Palette 26/87

NEET 2018 MCQ

An electron of mass m with an initial velocity $\overrightarrow v = {v_0}\widehat i$ (v₀ > 0) enters an electric field $\overrightarrow E = - {\overrightarrow E _0}\widehat i$ (E₀ = constant > 0) at t = 0. If $\lambda $₀ is its de-Broglie wavelength initially, then its de- Broglie wavelength at time t is

A

${{{\lambda _0}} \over {\left( {1 + {{e{E_0}} \over {m{v_0}}}t} \right)}}$

B

${{\lambda _0}\left( {1 + {{e{E_0}} \over {m{v_0}}}t} \right)}$

C

$\lambda $₀t

D

$\lambda $₀

Question 27: Palette 27/87

NEET 2018 MCQ

When the light of frequency 2${\upsilon _0}$ (where ${\upsilon _0}$ is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is v₁ . When the frequency of the incident radiation is increased to 5${\upsilon _0}$ , the maximum velocity of electrons emitted from the same plate is v₂ . The ratio of v₁ to v₂ is

A

1 : 2

B

1 : 4

C

4 : 1

D

2 : 1

Question 28: Palette 28/87

NEET 2017 MCQ

The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (kelvin) and mass m, is

A

${h \over {\sqrt {3mkT} }}$

B

${{2h} \over {\sqrt 3 mkT}}$

C

${{2h} \over {\sqrt {mkT} }}$

D

${h \over {\sqrt {mkT} }}$

Question 29: Palette 29/87

NEET 2017 MSQ

The photoelectric threshold wavelength of silver is 3250 $ \times $ 10^$-$10 m. The velocity of the electron ejected from a silver surface by ultraviolet light of wavelength 2536 $ \times $ 10^$-$10 m is
{Given h = 4.14 $ \times $ 10^$-$15 eV s and c = 3 $ \times $ 10⁸ m s^$-$1 ]

A

$ \approx $ 0.6 $ \times $ 10⁶ m s^$-$1

B

$ \approx $ 61 $ \times $ 10³ m s^$-$1

C

$ \approx $ 0.3 $ \times $ 10⁶ m s^$-$1

D

$ \approx $ 6 $ \times $ 10⁵ m s^$-$1

Question 30: Palette 30/87

NEET 2016 MCQ

Electrons of mass m with de-Broglie wavelength $\lambda $ fall on the target in an X-ray tube. The cutoff wavelength ($\lambda $₀) of the emitted X-ray is

A

$\lambda $₀ = ${{2mc{\lambda ^2}} \over h}$

B

${\lambda _0} = {{2h} \over {mc}}$

C

${\lambda _0} = {{2{m^2}{c^2}{\lambda ^3}} \over {{h^2}}}$

D

${\lambda _0} = \lambda $

Question 31: Palette 31/87

NEET 2016 MCQ

Photons with energy 5 eV are incifent on a cathode C in a photoelectric cell. The maximum energy of emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectrons will reach the anode A, if the stopping potential of A relative to C is

A

+ 3 V

B

+4 V

C

$-$1 V

D

$-$3 V

Question 32: Palette 32/87

NEET 2016 MCQ

An electron of mass m and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is

A

$c{\left( {2mE} \right)^{{1 \over 2}}}$

B

${1 \over c}{\left( {{{2m} \over E}} \right)^{{1 \over 2}}}$

C

${1 \over c}{\left( {{E \over {2m}}} \right)^{{1 \over 2}}}$

D

${\left( {{E \over {2m}}} \right)^{{1 \over 2}}}$

Question 33: Palette 33/87

NEET 2016 MCQ

When a metallic surface is illuminated with radiation of wavelength $\lambda $, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2 $\lambda $, the stopping potential is ${V \over 4}$. The threshold wavelength for the metallic surface is

A

${5 \over 2}\lambda $

B

3$\lambda $

C

4$\lambda $

D

5$\lambda $

Question 34: Palette 34/87

NEET 2015 MCQ

A photoelectric surface is illuminated successively by monochromatic light of wavelength $\lambda $ and $\lambda/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 surface of the material is
(h = Planck's constant, C = speed of light)

A

${{2hc} \over \lambda }$

B

${{hc} \over {3\lambda }}$

C

${{hc} \over {2\lambda }}$

D

${{hc} \over \lambda }$

Question 35: Palette 35/87

NEET 2015 MCQ

Light of wavelength 500 nm is incifent on a metal with work function 2.28 eV. The de Broglie wavelength of the emitted electron is

A

$ \ge $ 2.8 $ \times $ 10^$-$9 m

B

$ \le $ 2.8 $ \times $ 10^$-$12 m

C

< 2.8 $ \times $ 10^$-$10 m

D

< 2.8 $ \times $ 10^$-$9 m

Question 36: Palette 36/87

NEET 2015 MCQ

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

A

B

C

D

Question 37: Palette 37/87

NEET 2015 MCQ

A certain metallic surface is illuminated with monochromatic light of wavelength, $\lambda .$ The stopping potential for photo-electric current for this light is 3V₀. If the same surface is illuminated with light of wavelength 2 $\lambda $, the stopping potential is V₀. The threshold wavelength for this surface for photo-electric effect is

A

${\lambda \over 4}$

B

${\lambda \over 6}$

C

6$\lambda $

D

4$\lambda $

Question 38: Palette 38/87

NEET 2014 MCQ

When the energy of the incident radiation is increased nby 20%, the kinetic energy of the photoelectrons emitted from a metal surface increased from 0.5 eV to 0.8 eV. The work function of the metal is

A

0.65 eV

B

1.0 eV

C

1.3 eV

D

1.5 eV

Question 39: Palette 39/87

NEET 2014 MCQ

If the kinetic energy of the particle is increased to 16 times its previous value, the percentage change in the de Broglie wavelength of the particle is

A

25

B

75

C

60

D

50

Question 40: Palette 40/87

NEET 2013 MCQ

A source of light is placed at a distance of 50 cm from a photo cell and the stopping potential is found to be V₀. If the distance between the light source and photo cell is made 25 cm, the new stopping potential will be :

A

V₀/2

B

V₀

C

4V₀

D

2V₀

Question 41: Palette 41/87

NEET 2013 MCQ

The de-broglie wavelength of neutrons in thermal equilibrium at temperature T is

A

${{3.08} \over {\sqrt T }}\mathop A\limits^ \circ $

B

${{0.308} \over {\sqrt T }}\mathop A\limits^ \circ $

C

${{0.0308} \over {\sqrt T }}\mathop A\limits^ \circ $

D

${{30.8} \over {\sqrt T }}\mathop A\limits^ \circ $

Question 42: Palette 42/87

NEET 2013 MCQ

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

A

$\sqrt {{{2h\upsilon } \over m}} $

B

$2\sqrt {{{h\upsilon } \over m}} $

C

$\sqrt {{{h\upsilon } \over {\left( {2m} \right)}}} $

D

$\sqrt {{{h\upsilon } \over m}} $

Question 43: Palette 43/87

NEET 2013 MCQ

The wavelength $\lambda $_e of an electron and $\lambda $_p of a photon of same energy E are related by

A

${\lambda _p} \propto \sqrt {{\lambda _e}} $

B

${\lambda _p} \propto {1 \over {\sqrt {{\lambda _e}} }}$

C

${\lambda _p} \propto {\lambda _e}^2$

D

${\lambda _p} \propto {\lambda _e}$

Question 44: Palette 44/87

NEET 2013 MCQ

A parallel beam of fast moving electrons is incident normally on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the speed of the electrons is increased, which of the following statements is correct ?

A

The angular width of the central maximum will decrease.

B

The angular wifth of the central maximum will be unaffected.

C

Diffraction pattern is not observed on the screen in the case of electrons.

D

The angular width of the central maximum of the diffraction pattern will increase.

Question 45: Palette 45/87

NEET 2012 MCQ

If the momentum of an electron is changed by P, then the de Broglie wavelength associated with changes by 0.5%. The initial momentum of electron will be

A

200 P

B

400 P

C

${P \over {200}}$

D

100 P

Question 46: Palette 46/87

NEET 2012 MCQ

Two radiations of photons energies 1 eV and 2.5 eV, successively illuminate a photosensitive metallic surface of work function 0.5 eV. The ratio of the maximum speeds of the emitted electrons is

A

1 : 4

B

1 : 2

C

1 : 1

D

1 : 5

Question 47: Palette 47/87

NEET 2012 MCQ

A 200 W 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

A

1.5 $ \times $ 10²⁰

B

6 $ \times $ 10¹⁸

C

62 $ \times $ 10²⁰

D

3 $ \times $ 10¹⁹

Question 48: Palette 48/87

NEET 2012 MCQ

An $\alpha $-particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of 0.25 Wb/m². The de Broglie wavelength associated with the particle will be

A

1 $\mathop A\limits^ \circ $

B

0.1 $\mathop A\limits^ \circ $

C

10 $\mathop A\limits^ \circ $

D

0.01 $\mathop A\limits^ \circ $

Question 49: Palette 49/87

NEET 2012 MCQ

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

A

4 $ \times $ 10¹⁵ Hz

B

5 $ \times $ 10¹⁵ Hz

C

1.6 $ \times $ 10¹⁵ Hz

D

2.5 $ \times $ 10¹⁵ Hz

Question 50: Palette 50/87

NEET 2011 MCQ

The threshold frequency for a photosensitive metal is 3.3 $ \times $ 10¹⁴ Hz. If light of frequency 8.2 $ \times $ 10¹⁴ Hz is incident on this metal, the cut- off voltage for the photoelectron emission is nearly

A

1 V

B

2 V

C

3 V

D

5 V

Question 51: Palette 51/87

NEET 2011 MCQ

In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by

A

increasing the potential difference between the anode and filament

B

increasing the filament current

C

decreasing the filament current

D

decreasing the potential difference between the anode and flament

Question 52: Palette 52/87

NEET 2011 MCQ

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

A

1.8 V

B

1.3 V

C

0.5 V

D

2.3 V

Question 53: Palette 53/87

NEET 2011 MCQ

Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively illuminate a metallic surface whose work function is 0.5 eV successively. Ratio of maximum speeds of emitted electrons will be

A

1 : 4

B

1 : 2

C

1 : 1

D

1 : 5

Question 54: Palette 54/87

NEET 2011 MCQ

Photoelectric emission occurs only when the incident light has more than a certain minimum

A

power

B

wavelength

C

intensity

D

frequency

Question 55: Palette 55/87

NEET 2011 MCQ

Electrons used in an electron microscope are accelerated by a voltage of 25 kV. If the voltage is increased to 100 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

Question 56: Palette 56/87

NEET 2010 MCQ

When monochromatic radiation of intensity $I$ falls on a metal surface, the number of photoelectrons and their maximum kinetic energy are N and T respectively. If the intensity of radiation is 2$I$, the number of emitted electrons and their maximum kinetic energy are respectively

A

N and 2T

B

2N and T

C

2N and 2T

D

N and T

Question 57: Palette 57/87

NEET 2010 MCQ

The electron in the hydrogen atom jumps from excited state (n = 3) to its ground state (n = 1) and the photons thus emitted irradiate a photosensitive material. If the work function of the material is 5.1 eV, the stopping potential is estimated to be (the energy of the electron in n^th state E_n = ${{ - 13.6} \over {{n^2}}}eV$)

A

5.1 V

B

12.1 V

C

17.2 V

D

7 V

Question 58: Palette 58/87

NEET 2010 MCQ

The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work functions 5.01 eV, when ultraviolet light of 200 nm falls on it, must be

A

2.4 V

B

$-$ 1.2 V

C

$-$ 2.4 V

D

1.2 V

Question 59: Palette 59/87

NEET 2010 MCQ

A beam of cathode rays is subjected to crossed electric (E) and magnetic fields (B). The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by

(Where V is the potential difference between cathode and anode)

A

${{{B^2}} \over {2V{E^2}}}$

B

${{2V{B^2}} \over {{E^2}}}$

C

${{2V{E^2}} \over {{B^2}}}$

D

${{{E^2}} \over {2V{B^2}}}$

Question 60: Palette 60/87

NEET 2010 MCQ

A source S₁ is producing, 10¹⁵ photons per second of wavelength 5000 $\mathop A\limits^ \circ $. Another source S₂ is producing 1.02 $ \times $ 10¹⁵ photons per second of wavelength 5100 $\mathop A\limits^ \circ $. Then, (power of S₂)/(power of S₁) is equal to

A

1.00

B

1.02

C

1.04

D

0.98

Question 61: Palette 61/87

NEET 2009 MCQ

The number of photo electrons emitted for light of a frequency $\upsilon $ (higher than the threshold frequency ${\upsilon _0}$) is proportional to

A

threshold frequency $\left( {{\upsilon _0}} \right)$

B

intensity of light

C

frequency of light $\left( {{\upsilon _0}} \right)$

D

$\upsilon - {\upsilon _0}$

Question 62: Palette 62/87

NEET 2009 MCQ

Monochromatic light of wavelength 667 nm is produced by a helium neon laser. The power emitted is 9 mW. The number of photons arriving per sec. on the average at a target irradiated by this beam is

A

3 $ \times $ 10¹⁶

B

$9 \times {10^{15}}$

C

$3 \times {10^{19}}$

D

$9 \times {10^{17}}$

Question 63: Palette 63/87

NEET 2009 MCQ

The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three different radiations. Which one of the following is a correct statement?

A

Curves (a) and (b) represent incident radiations of same frequency but of different intensities.

B

Curves (b) and (c) represent incident radiations of different frquencies and different intensities.

C

Curves (b) and (C) represent incident radiations of same frequency having same intensity.

D

Curves (a) and (b) represent incident radiations of different frequencies and different intensities

Question 64: Palette 64/87

NEET 2008 MCQ

In the phenomenon of electric discharge through gases at low pressure, the coloured glow in the tube appears as a result of

A

collisions between the charged particles emitted from the cathode and the atoms of the gas

B

collision between different electrons of the atoms of the gas

C

excitation of electrons in the atoms

D

collision between the atoms of the gas

Question 65: Palette 65/87

NEET 2008 MCQ

A particle of mass 1 mg has the same wavelength as an electron moving with a velocity of 3 $ \times $ 10⁶ m s^$-$1. The velocity of the particle is

A

3 $ \times $ 10^$-$31 ms^$-$1

B

$2.7 \times {10^{ - 21}}\,m{s^{ - 1}}$

C

2.7 $ \times $ 10^$-$18 ms^$-$1

D

9 $ \times $ 10^$-$2 ms^$-$1

Question 66: Palette 66/87

NEET 2008 MCQ

The work function of a surface of a photosensitive material is 6.2 eV. The wavelength of the incident radiation for which the stopping potential is 5 V lies in the

A

infrared region

B

X-ray region

C

Ultraviolet region

D

Visible region

Question 67: Palette 67/87

NEET 2007 MCQ

Monochromatic light of frequency 6.0 $ \times $ 10¹⁴ Hz is produced by a laser. The power emitted is 2 $ \times $ 10^$-$3 W. The number of photons emitted, on the average, by the source per second is

A

5 $ \times {10^{16}}$

B

5 $ \times {10^{17}}$

C

5 $ \times {10^{14}}$

D

5 $ \times {10^{15}}$

Question 68: Palette 68/87

NEET 2007 MCQ

A 5 watt source emits monochromatic light of wavelength 5000 $\mathop A\limits^ \circ $. When placed 0.5 m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of 1.0 m, the number of photoelectrons liberated will be reduced by a factor of

A

8

B

16

C

2

D

4

Question 69: Palette 69/87

NEET 2007 MCQ

A beam of electron passes undeflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off, and the same magnetic field is maintained, the electrons move

A

in a circular orbit

B

along a parabolic path

C

along a straight line

D

in an elliptical orbit.

Question 70: Palette 70/87

NEET 2006 MCQ

The momentum of a photon of energy 1 MeV in kg m/s will be

A

5 $ \times $ 10^$-$22

B

0.33 $ \times $ 10⁶

C

7 $ \times $ 10^$-$24

D

10^$-$22

Question 71: Palette 71/87

NEET 2006 MCQ

In a discharge tube ionization of enclosed gas is produced due to collisions between

A

neutral gas atoms/molecules

B

positive ions and neutral atoms/molecules

C

negative electrons and neutral atoms/molecules

D

photons and neutral atoms/molecules.

Question 72: Palette 72/87

NEET 2006 MCQ

When photons of energy h$\upsilon $ fall on an aluminimum plate (of work function E₀), photoelectrons of maximum kinetic energy K are ejected. If the frequency of radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be

A

K + h$\upsilon $

B

K + E₀

C

2K

D

K.

Question 73: Palette 73/87

NEET 2006 MCQ

A photocell employs photoelectric effect to convert

A

change in the frequency of light into a change in the electric current

B

change in the frequency of light into a change in electric voltage

C

change in the intensity of illumination into a change in photoelectric current

D

change in the intensity of illumination into a change in the work function of the photocathode.

Question 74: Palette 74/87

NEET 2005 MCQ

A photosensitive metallic surface has work function, h$\upsilon $₀. If photons of energy $2h{\upsilon _0}$ fall on this surface, the electrons come out with a maximum velocity of 4 $ \times $ 10⁶ m/s. When the photon energy is increased to 5 h$\upsilon $₀, then maximum velocity of photoelectrons will be

A

2 $ \times $ 10⁷ m/s

B

2 $ \times $ 10⁶ m/s

C

8 $ \times $ 10⁶ m/s

D

8 $ \times $ 10⁵ m/s

Question 75: Palette 75/87

NEET 2005 MCQ

The work functions for metals A, B and C are respectively 1.92 eV, 2.0 eV and 5 eV. According to Einstein's equation the metals which will emit photoelectrons for a radiation of wavelength 4100 $\mathop A\limits^ \circ $ is/are

A

A only

B

A and B only

C

all the three metals

D

none

Question 76: Palette 76/87

NEET 2004 MCQ

According to Einstein's photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the frequency of incident radiation is

A

B

C

D

Question 77: Palette 77/87

NEET 2003 MCQ

J.J. Thomson's cathode-ray tube experiment demonstrated that

A

cathode rays are streams of negatively charged ions

B

all the maas of an atom is essentially in the nucleus

C

the e/m of electrons is much greater than the e/m of protons

D

the e/m ratio of the cathode-ray particles changes when a different gas is placed in the discharge tube

Question 78: Palette 78/87

NEET 2003 MCQ

A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m then

A

each emitted electron carries one quarter of the initial energy

B

number of electrons emitted is half the initial number

C

each emitted electron carries half the initial energy

D

number of electrons emitted is a quarter of the initial number

Question 79: Palette 79/87

NEET 2002 MCQ

The value of Planck's constant is

A

6.63 $ \times $ 10^$-$34 J/sec.

B

6.63 $ \times $ 10^$-$34 kg-m²/sec

C

6.63 $ \times $ 10^$-$34 kg-m²

D

6.63 $ \times $ 10^$-$34 J-sec.

Question 80: Palette 80/87

NEET 2002 MCQ

When ultraviolet rays incident on metal plate then photoelectric effect does not occur, it occurs by incidence of

A

infrared rays

B

X-rays

C

radio wave

D

micro wave

Question 81: Palette 81/87

NEET 2002 MCQ

Which of the following is not the property of cathode rays ?

A

In produces heating effect

B

It does not deflect in electric field

C

It casts shadow

D

It produces fluorscence.

Question 82: Palette 82/87

NEET 2002 MCQ

If particles are moving with same velocity, then which has maximum de Broglie wavelength?

A

proton

B

$\alpha $-particle

C

neutron

D

$\beta $-particle

Question 83: Palette 83/87

NEET 2001 MCQ

Which one among the following shows particle nature of light?

A

photo electric effect

B

interference

C

refraction

D

polarization.

Question 84: Palette 84/87

NEET 2001 MCQ

A photo-cell is illuminated by a source of light, which is placed at a distance d from the cell. If the distance become d/2, then number of electrons emitted per second, will be

A

remain same

B

four times

C

two times

D

one-fourth

Question 85: Palette 85/87

NEET 2001 MCQ

In Thomson mass spectrograph $\overrightarrow E \bot \overrightarrow B $ then the velocity of electron beam will be

A

${{\left| {\overrightarrow E } \right|} \over {\left| {\overrightarrow B } \right|}}$

B

$\overrightarrow E \times \overrightarrow B $

C

${{\left| {\overrightarrow B } \right|} \over {\left| {\overrightarrow E } \right|}}$

D

${{{{\overrightarrow E }^2}} \over {{{\overrightarrow B }^2}}}$

Question 86: Palette 86/87

NEET 2000 MCQ

By photoelectric effect, Einstein proved

A

E = h$\upsilon $

B

K.E. = ${1 \over 2}$ mv²

C

E = mc²

D

E = ${{ - Rh{c^2}} \over {{n^2}}}$

Question 87: Palette 87/87

NEET 2000 MCQ

Who evaluated the mass of electron infirectly with help of charge

A

Thomson

B

Millikan

C

Rutherford

D

Newton