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Explore popular questions from Dual Nature of Matter and Radiation for NEET. This collection covers Dual Nature of Matter and Radiation previous year NEET questions hand picked by experienced teachers.

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Dual Nature of Matter and Radiation

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Q 1. A particle of mass 1{tex} \mathrm { mg } {/tex} has the same wavelength as an electron moving with a velocity of {tex} 3 \times 10 ^ { 6 } \mathrm { ms } ^ { - 1 } {/tex} . The velocity of the particle is:

{tex} 2.7 \times 10 ^ { - 18 } \mathrm { ms } ^ { - 1 } {/tex}

B

{tex} 9 \times 10 ^ { - 2 } \mathrm { ms } ^ { - 1 } {/tex}

C

{tex} 3 \times 10 ^ { - 31 } \mathrm { ms } ^ { - 1 } {/tex}

D

{tex} 2.7 \times 10 ^ { - 21 } \mathrm { ms } ^ { - 1 } {/tex}

Explanation

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Q 2. An electron of mass {tex} \mathrm { m } {/tex} and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is:

{tex} \frac { 1 } { \mathrm { c } } \left( \frac { \mathrm { E } } { 2 \mathrm { m } } \right) ^ { \frac { 1 } { 2 } } {/tex}

B

{tex} \left( \frac { E } { 2 m } \right) ^ { \frac { 1 } { 2 } } {/tex}

C

{tex} c ( 2 m E ) ^ { \frac { 1 } { 2 } } {/tex}

D

{tex} \frac { 1 } { c } \left( \frac { 2 m } { E } \right) ^ { \frac { 1 } { 2 } } {/tex}

Explanation

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Q 3. All electrons ejected from a surface by incident light of wavelength 200 nm can be stopped before travelling 1{tex} \mathrm { m } {/tex} in the direction of uniform electric field of {tex}4 \mathrm { N } / \mathrm { C } {/tex}. The work function of the surface is

A

4{tex} \mathrm { eV } {/tex}

B

6.2 {tex} \mathrm { eV } {/tex}

C

2 {tex} \mathrm { eV } {/tex}

2.2 {tex} \mathrm { eV } {/tex}

Explanation

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Q 4. An X-ray tube is operated at 15{tex} \mathrm { kV } {/tex} . Calculate the upper limit of the speed of the electrons striking the target.

{tex} 7.26 \times 10 ^ { 7 } \mathrm { m } / \mathrm { s } {/tex}

B

{tex} 7.62 \times 10 ^ { 9 } \mathrm { m } / \mathrm { s } {/tex}

C

{tex} 7.62 \times 10 ^ { 7 } \mathrm { cm } / \mathrm { s } {/tex}

D

{tex} 7.26 \times 10 ^ { 9 } \mathrm { m } / \mathrm { s } {/tex}

Explanation

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Q 5. A and B are two metals with threshold frequencies {tex} 1.8 \times 10 ^ { 14 } \mathrm { Hz } {/tex} and {tex} 2.2 \times 10 ^ { 14 } \mathrm { Hz } {/tex} . Two identical photons of energy 0.825 eV each are incident on them. Then photoelectrons are emitted in ( Take h = {tex} 6.6 \times 10 ^ {- 34 } {/tex} Js)

A

B alone

A alone

C

neither A nor B

D

both {tex} \mathrm { A } {/tex} and {tex} \mathrm { B } {/tex}

Explanation

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Q 6. If {tex} \mathrm { E } _ { 1 } , \mathrm { E } _ { 2 } , \mathrm { E } _ { 3 } {/tex} are the respective kinetic energies of an electron, an alpha-particle and a proton, each having the same de-Broglie wavelength, then

{tex} \mathrm { E } _ { 1 } > \mathrm { E } _ { 3 } > \mathrm { E } _ { 2 } {/tex}

B

{tex} \mathrm { E } _ { 2 } > \mathrm { E } _ { 3 } > \mathrm { E } _ { 1 } {/tex}

C

{tex} \mathrm { E } _ { 1 } > \mathrm { E } _ { 2 } > \mathrm { E } _ { 3 } {/tex}

D

{tex} \mathrm { E } _ { 1 } = \mathrm { E } _ { 2 } = \mathrm { E } _ { 3 } {/tex}

Explanation

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Q 7. Which of the following when falls on a metal will emit photoelectrons?

UV radiations

B

Infrared radiation

C

Radio waves

D

Microwaves

Explanation

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Q 8. The stopping potential V0 versus frequency (ν) plot of a substance is shown in figure, the threshold wavelength is


A

{tex} 5 \times 10 ^ { 14 } \mathrm { m } {/tex}

6000 {tex}{\text{Å}}{/tex}

C

5000 {tex}{\text{Å}}{/tex}

D

Cannot be estimated from given data

Explanation

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Q 9. A 200 W sodium street lamp emits yellow light of wavelength 0.6{tex} \mu m {/tex} . Assuming it to be 25{tex} \% {/tex} efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is

{tex} 1.5 \times 10 ^ { 20 } {/tex}

B

{tex} 6 \times 10 ^ { 18 } {/tex}

C

{tex} 62 \times 10 ^ { 20 } {/tex}

D

{tex} 3 \times 10 ^ { 19 } {/tex}

Explanation

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Q 10. A proton has kinetic energy {tex} \mathrm { E } = 100 \mathrm { keV } {/tex} which is equal to that of a photon. The wavelength of photon is {tex} \lambda _ { 2 } {/tex} and that of proton is {tex} \lambda _ { 1 } . {/tex} The ratio of {tex} \lambda _ { 2 } / \lambda _ { 1 } {/tex} is proportional to

A

{tex} \mathrm { E } ^ { 2 } {/tex}

B

{tex} \mathrm { E } ^ { 1 / 2 } {/tex}

C

{tex} E ^ { - 1 } {/tex}

{tex} \mathrm { E } ^ { - 1 / 2 } {/tex}

Explanation

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Q 11. In photoelectric effect the work function of a metal is 3.5{tex} \mathrm { eV } {/tex} . The emitted electrons can be stopped by applying a potential of {tex} - 1.2 \mathrm { V } . {/tex} Then

the energy of the incident photon is 4.7{tex} \mathrm { eV } {/tex}

B

the energy of the incident photon is 2.3{tex} \mathrm { eV } {/tex}

C

if higher frequency photon be used, the photoelectric current will rise

D

when the energy of photon is {tex} 3.5 \mathrm { eV } , {/tex} the photoelectric current will be maximum

Explanation

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Q 12. The threshold frequency for a metallic surface corresponds to an energy of 6.2{tex} \mathrm { eV } {/tex} and the stopping potential for a radiation incident on this surface is 5{tex} \mathrm { V } {/tex} . The incident radiation lies in

ultra-violet region

B

infra-red region

C

visible region

D

X-ray region

Explanation

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Q 13. When photons of energy hv fall on an aluminium plate (of {tex} \left. \text { work function } \mathrm { E } _ { 0 } \right) , {/tex} photoclectrons of maximum kinetic energy {tex} \mathrm { K } {/tex} are ejected. If the frequency of the radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be

A

2{tex} \mathrm { K } {/tex}

B

{tex} K {/tex}

{tex} \mathrm { K } + \mathrm { h } \mathrm { v } {/tex}

D

{tex} \mathrm { K } + \mathrm { E } _ { 0 } {/tex}

Explanation

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Q 14. Which metal will be suitable for a photoelectric cell using light of wavelength 4000 Å. The work functions of sodium and copper are respectively 2.0 eV and 4.0 eV

Sodium

B

Copper

C

Both option a and b

D

None of these

Explanation

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Q 15. The maximum velocity of an electron emitted by light of wavelength {tex} \lambda {/tex} incident on the surface of a metal of work- function {tex} \phi {/tex} is

A

{tex} \sqrt { \frac { 2 ( \mathrm { hc } + \lambda \phi ) } { \mathrm { m } \lambda } } {/tex}

B

{tex} \frac { 2 ( \mathrm { hc } + \lambda \phi ) } { \mathrm { m } \lambda } {/tex}

{tex} \sqrt { \frac { 2 ( \mathrm { hc } - \lambda \phi ) } { \mathrm { m } \lambda } } {/tex}

D

{tex} \sqrt { \frac { 2 ( \mathrm { h } \lambda - \phi ) } { \mathrm { m } } } {/tex}

Explanation

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Q 16. If the kinetic energy of a free electron doubles, it's deBroglie wavelength changes by the factor

A

2

B

{tex} \frac { 1 } { 2 } {/tex}

C

{tex} \sqrt { 2 } {/tex}

{tex} \frac { 1 } { \sqrt { 2 } } {/tex}

Explanation

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Q 17. Radiations of two photon's energy, twice and ten times the work function of metal are incident on the metal surface successsively. The ratio of maximum velocities of photoelectrons emitted in two cases is

A

{tex} 1 : 2 {/tex}

{tex} 1 : 3 {/tex}

C

{tex} 1 : 4 {/tex}

D

{tex} 1 : 1 {/tex}

Explanation

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Q 18. The cathode of a photoelectric cell is changed such that the work function changes from {tex} \mathrm { W } _ { 1 } {/tex} to {tex} \mathrm { W } _ { 2 } \left( \mathrm { W } _ { 2 } > \mathrm { W } _ { 1 } \right) {/tex} . If the current before and after changes are {tex} \mathrm { I } _ { 1 } {/tex} and {tex} \mathrm { I } _ { 2 } , {/tex} all other conditions remaining unchanged, then (assuming hv > {tex}{ W } _ { 2 }{/tex} )

{tex} I _ { 1 } = I _ { 2 } {/tex}

B

{tex} I _ { 1 } < I _ { 2 } {/tex}

C

{tex} I _ { 1 } > I _ { 2 } {/tex}

D

{tex} I _ { 1 } < I _ { 2 } < 2 I {/tex}

Explanation

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Q 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{tex} \mathrm { V } {/tex} . The threshold frequency of the materials is:

A

{tex} 4 \times 10 ^ { 15 } \mathrm { Hz } {/tex}

B

{tex} 5 \times 10 ^ { 15 } \mathrm { Hz } {/tex}

{tex} 1.6 \times 10 ^ { 15 } \mathrm { Hz } {/tex}

D

{tex} 2.5 \times 10 ^ { 15 } \mathrm { Hz } {/tex}

Explanation


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Q 20. Photoelectric work function of a metal is 1eV. Light of wavelength {tex}\lambda = 3000 {\text{Å}}{/tex} falls on it. The photo electrons come out with velocity

A

10 metres/sec

B

{tex} 10 ^ { 2 } {/tex} metres/sec

C

{tex} 10 ^ { 4 } {/tex} metres/sec

{tex} 10 ^ { 6 } {/tex} metres/sec

Explanation

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Q 21. In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by

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 filament

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Q 22. The ratio of the respective de Broglie wavelengths associated with electrons accelerated from rest with the voltages {tex} 100 \mathrm { V } , 200 \mathrm { V } {/tex} and 300{tex} \mathrm { V } {/tex} is

A

{tex} 1 : 2 : 3 {/tex}

B

{tex} 1 : 4 : 9 {/tex}

{tex} 1 : \frac { 1 } { \sqrt { 2 } } : \frac { 1 } { \sqrt { 3 } } {/tex}

D

{tex} 1 : \frac { 1 } { 2 } : \frac { 1 } { 3 } {/tex}

Explanation