Maharashtra Board Class 8 Maths Solutions

Expert Teachers at LearnCram.com has created Maharashtra board 8th Standard maths Solutions. You can also Download Maharashtra Board 8th Standard Maths Solutions PDF to help you to revise complete Syllabus and score more marks in your examinations.

Maharashtra State Board Class 8 Maths Solutions

Maharashtra Board Class 8 Maths Chapter 1 Rational and Irrational Numbers

Maharashtra Board Class 8 Maths Chapter 2 Parallel Lines and Transversals

Maharashtra Board Class 8 Maths Chapter 3 Indices and Cube Root

Maharashtra Board Class 8 Maths Chapter 4 Altitudes and Medians of a Triangle

Maharashtra Board Class 8 Maths Chapter 5 Expansion Formulae

Maharashtra Board Class 8 Maths Chapter 6 Factorisation of Algebraic Expressions

Maharashtra Board Class 8 Maths Chapter 7 Variation

Maharashtra Board Class 8 Maths Chapter 8 Quadrilateral: Constructions and Types

Maharashtra Board Class 8 Maths Chapter 9 Discount and Commission

Maharashtra Board Class 8 Maths Miscellaneous Exercise 1

Maharashtra Board Class 8 Maths Chapter 10 Division of Polynomials

Maharashtra Board Class 8 Maths Chapter 11 Statistics

Maharashtra Board Class 8 Maths Chapter 12 Equations in One Variable

Maharashtra Board Class 8 Maths Chapter 13 Congruence of Triangles

Maharashtra Board Class 8 Maths Chapter 14 Compound Interest

Maharashtra Board Class 8 Maths Chapter 15 Area

Maharashtra Board Class 8 Maths Chapter 16 Surface Area and Volume

Maharashtra Board Class 8 Maths Chapter 17 Circle: Chord and Arc

Maharashtra Board Class 8 Maths Miscellaneous Exercise 2

Maharashtra Board Class 9 Maths Solutions

Expert Teachers at LearnCram.com has created Maharashtra board 9th Standard maths Solutions. You can also Download Maharashtra Board 9th Standard Maths Solutions PDF to help you to revise complete Syllabus and score more marks in your examinations.

Maharashtra State Board Class 9 Maths Solutions

Maharashtra State Board Class 9 Maths Solutions Part-1

Maharashtra Board Class 9 Maths Chapter 1 Sets

Maharashtra Board Class 9 Maths Chapter 2 Real Numbers

Maharashtra Board Class 9 Maths Chapter 3 Polynomials

Maharashtra Board Class 9 Maths Chapter 4 Ratio and Proportion

Maharashtra Board Class 9 Maths Chapter 5 Linear Equations in Two Variables

Maharashtra Board Class 9 Maths Chapter 6 Financial Planning

Maharashtra Board Class 9 Maths Chapter 7 Statistics

Maharashtra State Board Class 9 Maths Solutions Part-2

Maharashtra Board Class 9 Maths Chapter 1 Basic Concepts in Geometry

Maharashtra Board Class 9 Maths Chapter 2 Parallel Lines

Maharashtra Board Class 9 Maths Chapter 3 Triangles

Maharashtra Board Class 9 Maths Chapter 4 Constructions of Triangles

Maharashtra Board Class 9 Maths Chapter 5 Quadrilaterals

Maharashtra Board Class 9 Maths Chapter 6 Circle

Maharashtra Board Class 9 Maths Chapter 7 Co-ordinate Geometry

Maharashtra Board Class 9 Maths Chapter 8 Trigonometry

Maharashtra Board Class 9 Maths Chapter 9 Surface Area and Volume

Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter

Free PDF Download of CBSE Physics Multiple Choice Questions for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter. Physics MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Physics Dual Nature of Radiation and Matter MCQs Pdf with Answers to know their preparation level.

Dual Nature of Radiation and Matter Class 12 Physics MCQs Pdf

Dual Nature of Radiation and Matter MCQ Questions with Answers Pdf Question 1. Light of frequency 1.9 times the threshold frequency is incident on a photosensitive material. If the frequency is halved and intensity is doubled, the photocurrent becomes
(a) quadrupled
(b) doubled
(c) halved
(d) zero

Answer/Explanation

Answer: d
Explaination: (d) As vi = 0.95 v0. No photoelectric emission takes place.


Dual Nature of Matter And Radiation Class 12 MCQ Question 2. Threshold wavelength for a metal having work function W0 is X. What is the threshold wavelength for the metal having work function 2W0?
(a) 4λ
(b) 2λ
(c) λ/2
(d) λ/4

Answer/Explanation

Answer: c
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 17


MCQ on Dual Nature of Matter And Radiation Question 3. Radiations of frequency v are incident on a photosensitive metal. The maximum K.E. of the photoelectrons is E. When the frequency of the incident radiation is doubled, what is the maximum kinetic energy of the photoelectrons?
(a) 2E
(b) 4E
(c) E + hv
(d) E – hv

Answer/Explanation

Answer: c
Explaination: (c) Using Einstein’s photoelectric equation hv – w0 = E


4. Maximum kinetic energy (Ek) of a photoelectron varies with frequency (v) of the incident radiation as
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 2
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 3

Answer/Explanation

Answer: d
Explaination: (d) Using Einstein’s photoelectric equation hv = hv0 + Ek


Physics MCQs for Class 11 With Answers Pdf Question 5. The stopping potential V0 for photoelectric emission from a metal surface is plotted along y-axis and frequency v of incident light along x-axis. A straight line is obtained as shown. Planck’s constant is given by
Physics MCQ Questions for Class 12 Pdf Download
(a) slope of the line
(b) product of the slope of the line and charge on electron
(c) intercept along y-axis divided by charge on the electron
(d) product of the intercept along x-axis and mass of the electron

Answer/Explanation

Answer: b
Explaination: (b) Using Einstein’s photoelectric equation


6. The energy of photon of wavelength 450 nm is
(a) 2.5 × 10-17 J
(b) 1.25 × 10-17 J
(c) 4.4 × 10-19 J
(d) 2.5 × 10-19 J

Answer/Explanation

Answer: c
Explaination:
Physics Multiple Choice Questions With Answers for Class 12 Pdf


7. The kinetic energy of an electron is 5 eV. Calculate the de broglie wavelength associated with it. (h = 6.6 × 10-34 Js, me = 9.1 × 10-31 kg)
(a) 5.47 Å
(b) 10.9 Å
(c) 2.7 Å
(d) None of these

Answer/Explanation

Answer: c
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 19


Photoelectric Effect Multiple Choice Questions and Answers Pdf8. The slope of the stopping potential versus ‘ frequency graph for photoelectric effect is equal to
Photoelectric Effect Multiple Choice Questions and Answers Pdf
(a) h
(b) he
(c) h/e
(d) e

Answer/Explanation

Answer: c
Explaination:
(c) Using Einstein’s equation for photoelectric effect
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 20


Class 12 Physics MCQ Chapter Wise Question 9. A proton and an α-particle are accelerated by the same potential difference. The ratio of their de broglie wavelengths (λp, λα) is
(a) 1
(b) 2
(c) √8
(d) \(\frac{1}{\sqrt{8}}\)

Answer/Explanation

Answer: c
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 21


Class 12 Physics MCQ Chapter Wise Question 10. Work function of three metals A, B and C are 4.5 eV, 4.3 eV and 3.5 eV respectively. If a light of wavelength 4000 Å is incident on the metals then
(a) photoelectrons are emitted from A.
(b) photoelectrons are emitted from B.
(c) photoelectrons are emitted from C.
(d) photoelectrons are emitted from all the metals.

Answer/Explanation

Answer: d
Explaination:
(d) Since energy of incident photon
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 22


11. Which of the following figure represents the variation of particle momentum and associated de Broglie wavelength?
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 7

Answer/Explanation

Answer: d
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 23


12. According to Einstein’s photoelectric equation the plot of the kinetic energy of the emitted photo-electrons from a metal vs the frequency of the incident radiation gives a straight line whose slope
(a) depends on the nature of the metal used.
(b) depends on the intensity of the radiation.
(c) depends both on the intensity of the radiation and the metal used.
(d) is the same for all metals and independent of the intensity of the radiation.

Answer/Explanation

Answer: d
Explaination: (d) Since slope = \(\frac{h}{e}\)


13. If K.E. of free electron is doubled, its de Broglie wavelength will change by factor
(a) \(\frac{1}{\sqrt{8}}\)
(b) √2
(c) \(\frac{1}{2}\)
(d) 2

Answer/Explanation

Answer: a
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 24


14. For a given kinetic energy which of the following has smallest de Broglie wavelength?
(a) Electron
(b) Proton
(c) Deutron
(d) a-particle

Answer/Explanation

Answer: d
Explaination:
(d) Since de Broglie wavelength
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 25
particle, mass of ∝-particle is maximum.


15. A particle is dropped from a height H. The de Broglie wavelength of the particle as a function of height is proportional to [NCERT Exemplar]
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 11

Answer/Explanation

Answer: d
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 26


16. A proton, a neutron, an electron and an a-particle have same energy. Then their de Broglie wavelengths compare as [NCERT Exemplar]
(a)λp = λn > λe > λα
(b) λα < λp = λn < λe
(‘C) λe < λp = λn > λα
(d) λe = λp = λn = λα

Answer/Explanation

Answer: b
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 27


17. In photoelectric effect what determines the maximum velocity of electron reacting the collector?
(a) Frequency of incident radiation alone
(b) Work function of metal
(c) Potential difference between the emitter and the collector
(d) All of these

Answer/Explanation

Answer: d
Explaination: (d) As per Einstein’s photoelectric equation


18. A Proton and an a-particle have the same de Broglie wavelength. What is same for both of them?
(a) Mass
(b) Energy
(c) Frequency
(d) Momentum

Answer/Explanation

Answer: d
Explaination: (d) Since λ = \(\frac{h}{p}\), for the same wavelength momentum is also same.


19. The wavelength of a photon needed to remove a proton from a nucleus which is bound to the nucleus with 1 MeV energy is nearly [NCERT Exemplar]
(a) 1.2 nm
(b) 1.2 × 10-3 nm
(c) 1.2 × 10-6 nm
(d) 1.2 × 101 nm

Answer/Explanation

Answer: b
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 28


20. An electron is moving with an initial velocity v = v0i and is in a magnetic field B = B0 j. Then, its de Broglie wavelength [NCERT Exemplar]
(a) remains constant.
(b) increases with time.
(c) decreases with time.
(d) increases and decreases periodically.

Answer/Explanation

Answer: a
Explaination:
(a) F = q(v × B) = F = qvB sin θ. As this force is perpendicular to v and B, so the magnitude of v will not change, i.e. momentum (p = mv) will remain constant in magnitude
De Broglie wavelength λ = \(\frac{h}{m v}\) remams constant
∴ Comparing wavelengths of proton and neutron, mp = mn, hence λp = λn.


21. Who established that electric charge is quantised?
(a) J.J. Thomson
(b) William Crookes
(c) R.A. Millikan
(d) Wilhelm Rontgen

Answer

Answer: c


22. Cathode rays were discovered by
(a) Maxwell Clerk James
(b) Heinrich Hertz
(c) William Crookes
(d) J.J. Thomson

Answer

Answer: c


23. The minimum energy required for the electron emission from the metal surface can be supplied to the free electrons by which of the following physical processes?
(a) Thermionic emission
(b) Field emission
(c) Photoelectric emission
(d) All of these

Answer

Answer: d


24. The phenomenon of photoelectric emission was discovered in 1887 by
(a) Albert Einstein
(b) Heinrich Hertz
(c) Wilhelm Hallwachs
(d) Philipp Lenard

Answer

Answer: b


25. A metal surface ejects electrons when hit by green light but nothing when hit by yellow light. The electrons will be ejected when the surface is hit by
(a) blue light
(b) heat rays
(c) infrared light
(d) red light

Answer

Answer: a


26. Which of the following statements is correct regarding the photoelectric experiment?
(a) The photocurrent increases with intensity of light.
(b) Stopping potential increases with increase in intensity of incident light.
(c) The photocurrent increases with increase in frequency.
(d) All of these

Answer

Answer: a


27. In photoelectric effect, the photocurrent
(a) depends both on intensity and frequency of the incident light.
(b) does not depend on the frequency of incident light but depends on the intensity of the inci-dent light.
(c) decreases with increase in frequency of inci-dent light.
(d) increases with increase in frequency of inci-dent light.

Answer

Answer: b


28. The maximum value of photoelectric current is called
(a) base current
(b) saturation current
(c) collector current
(d) emitter current

Answer

Answer: b


29. In photoelectric effect, the photoelectric current is independent of
(a) intensity of incident light
(b) potential difference applied between the two electrodes
(c) the nature of emitter material
(d) frequency of incident light

Answer

Answer: d


30. In photoelectric effect, stopping potential depends on
(a) frequency of incident light
(b) nature of the emitter material
(c) intensity of incident light
(d) both (a) and (b)

Answer

Answer: d


31. According to Einstein’s photoelectric equation, the graph of kinetic energy of the photoelectron emitted from the metal versus the frequency of the incident radiation gives a straight line graph, whose slope
(a) depends on the intensity of the incident radi-ation.
(b) depends on the nature of the metal and also on the intensity of incident radiation.
(c) is same for all metals and independent of the intensity of the incident radiation.
(d) depends on the nature of the metal.

Answer

Answer: c


32. The figure shows stopping V0A potential V0 and frequency o for two different metallic surfaces A and B. The work function of A, as compared to that of B is
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter
(a) less
(b) more
(c) equal
(d) nothing can be said

Answer

Answer: a


33. Which phenomenon best supports the theory that matter has a wave nature?
(a) Electron momentum
(b) Electron diffraction
(c) Photon momentum
(d) Photon diffraction

Answer

Answer: b


34. The figure shows the variation of photocurrent with anode potential for a photosensitive surface for three different radiations. Let Ia, Ib and Ic be the intensities and va, vb. and vcbe the frequencies for the curves a, b and c respectively. Then the correct relation is
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 5
(a) va = vb and Ia ≠ Ib
(b) va = vc and Ia = Ic
(c) va = vb and Ia = Ib
(d) vb = vc and Ib = Ic

Answer

Answer: a


35. The photoelectric effect can be explained by
(a) Corpuscular theory of light
(b) Wave nature of light
(c) Bohr’s theory
(d) Quantum theory of light

Answer

Answer: d


36. Work function of metal is
(a) the minimum energy required to free an electron from surface against coulomb forces.
(b) the minimum energy required to free an », nucleon.
(c) the minimum energy to ionise an atom.
(d) the minimum energy required to eject an electron orbit.

Answer

Answer: a


37. The rest mass of a photon of wavelength X is
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 8

Answer

Answer: a


38. Photoelectric effect is based on the law of conservation of
(a) energy
(b) mass
(c) linear momentum
(d) angular momentum

Answer

Answer: a


39. Einstein’s photoelectric equation is:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 9
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 10

Answer

Answer: a


40. In photoelectric effect, the number of photoelectrons emitted is proportional to
(a) intensity of incident beam. –
(b) frequency of incident beam.
(c) velocity of incident beam.
(d) work function of photo cathode.

Answer

Answer: a


41. Which of the following shows particle nature of light?
(a) Photoelectric effect
(b) Refraction
(c) Interference
(d) Polarisation

Answer

Answer: a


42. Relativistic corrections become necessary when the expression for the kinetic energy 1/2 mv², becomes comparable with mc², where m is the mass of the particle. At what de Broglie wavelength, will relativistic corrections become important for an electron?
(a) λ = 10 nm
(b) λ = 10-1 nm
(c) λ = 10-4nm
(d) λ = 10-3 nm

Answer

Answer: c


43. Two particles A1 and A2 of masses m1, m2(m1 > m2) have the same de Broglie wavelength. Then,
(a) their momenta are the same.
(b) their energies are the same.
(c) energy of A1 is greater than the energy of A2
(d) energy of A1 is equal to the energy of A2

Answer

Answer: a


44. Photons absorbed in a matter are converted to heat. A source emitting h photon/sec of frequency v is used to convert 1 kg or ice at 0°C to water at 0°C. Then, the time T taken for the conversion
(a) increases with increasing n, with v fixed
(b) decreases with n fixed, v increasing.
(c) does not remain constant with n and v changing such that nv = constant
(d) increases when the product nv increases.

Answer

Answer: b


45. A particle moves in a closed orbit around the origin, due to a force which is directed towards the origin. The de Broglie wavelength of the particle varies cyclically between two values λ1, λ2 with λ1 > λ2. Which following statements are true?
(a) The particle could not be moving in a circular orbit with origin as centre.
(b) The particle could not be moving in an elliptic orbit with origin as its focus.
(c) When the de Broglie wavelength is λ1 the particle is nearer the origin than when its value is λ2.
(d) When the de Broglie wavelength λ2, the particle is nearer the origin than when its value λ1.

Answer

Answer: d


46. Consider the following statements:
I. According to de Broglie hypothesis, particles have wave-like characteristics.
II. When an electron and a proton have the same de Broglie wavelength, they will have equal momentum.
Which of the above statements is/are correct?
(a) I only
(b) II only
(c) both I and II
(d) neither I nor II

Answer

Answer: c


47. Maximum photoelectric current at particular intensity of incident radiation, which becomes independent of anode potential is known as __________ .

Answer/Explanation

Answer:
Explaination: saturation current


48. Stopping potential is of intensity of incident radiation but proportional to __________ of the radiation.

Answer/Explanation

Answer:
Explaination: independent, frequency


49. Kinetic energy and stopping potential are zero, when frequency of incident radiation is equal to __________ .

Answer/Explanation

Answer:
Explaination: threshold frequency


50. According to Planck’s quantum theory of radiation, an electromagnetic wave travels in the form packets of energy called __________ .

Answer/Explanation

Answer:
Explaination: photon


51. __________ experiment has varified and confirmed the wave nature of electrons.

Answer/Explanation

Answer:
Explaination: Davisson and Germer


52. Photoelectric emission occurs only when the frequency of incident radiation is __________ than threshold frequency.

Answer/Explanation

Answer:
Explaination: greater


53. Photoelectric emission is an __________ process.

Answer/Explanation

Answer:
Explaination: instantaneous


54. De Broglie wavelength associated with an electron beam accelerated through a potential difference V is __________ proportional to √V.

Answer/Explanation

Answer:
Explaination: inversely


55. __________ is the minimum amount of energy required to cause photoelectric emission.

Answer/Explanation

Answer:
Explaination: Wok function


56. Wave associated with the material particle is known as __________ .

Answer/Explanation

Answer:
Explaination: matter wave


57. Name the phenomenon which shows the quantum nature of electromagnetic radiation. [AI2017]

Answer/Explanation

Answer:
Explaination: Photoelectric effect.


58. Define the term ‘threshold frequency’ in relation to photoelectric effect. [Delhi 2019, Foreign 2011]

Answer/Explanation

Answer:
Explaination:
Threshold frequency: For every metal surface, there is a minimum frequency of incident radiation, below which the photoelectric emission does not take place no matter what the intensity of incident radiation is and for how long the radiations are allowed to fall on the metal. This frequency is called threshold frequency.


59. Show the variation of photocurrent with collector plate potential for different frequencies but same intensity of incident radiation. [AI 2017, Foreign 2011]

Answer/Explanation

Answer:
Explaination:
For same intensity but different frequencies v1 > v2 > v3 of incident radiation.
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 29


60. In photoelectric effect, why should the photoelectric current increases as the intensity of monochromatic radiation incident on a photosensitive surface is increased? Explain. [Foreign 2014]

Answer/Explanation

Answer:
Explaination:
An increase in intensity means increase in number of photons and thus, increase in photoelectric current.


61. Show the variation of photocurrent with collector plate potential for different intensities but same frequency of incident radiation. [Delhi 2019, AI 2017, Foreign 2011]

Answer/Explanation

Answer:
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 30


62. What is the rest mass of a photon?

Answer/Explanation

Answer:
Explaination: The rest mass of a photon is zero.


63. The given graph shows the variation of photoelectric current (I) versus applied voltage (V) for two different photosensitive materials and for two different intensities of the incident radiation. Identify the pairs of curves that correspond to different materials but same intensity of incident radiation. [Delhi 2013]
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 12

Answer/Explanation

Answer:
Explaination: The materials with same intensity of incident light are 1 and 3; 2 and 4.


64. The graph shows the variation of stopping potential with frequency of incident radiation for two photosensitive metals A and B. Which one of the two has higher value of work function? Justify your answer. [Chennai 2019, Dehradun 2019]
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 13

Answer/Explanation

Answer:
Explaination:
As threshold frequency of metal A is greater, its work function, Φ = hv0, will also be greater than that of B.


65. For a given photosensitive material and with a source of constant frequency of incident radiation, how does the photocurrent vary with the intensify of incident light? [Delhi 2014, AI 2011C]
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 14

Answer/Explanation

Answer:
Explaination:
The photoelectric current increases linearly with the intensity of light as shown in the figure.
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 31


66. Ultraviolet radiations of different frequencies v1 and v2 are incident on two photosensitive materials having work functions W1 and W2 (W1 > W2) respectively. The kinetic energy of the emitted electrons is same in both the cases. Which one of the two radiations will be of higher frequency?

Answer/Explanation

Answer:
Explaination:
v1 > v2. As W1 > W2 and K.E. is same. From the relation,
hv = hv0 + \(\frac{1}{2}\) mv²
and hv0 = W= work function


67. Two beams, one of red light and the other of blue light, of the same intensity are incident on a metallic surface to emit photoelectrons. Which one of the two beams emits electrons of greater kinetic energy? [HOTS]

Answer/Explanation

Answer:
Explaination:
The blue light emits the electrons of greater K.E., as vb > vr.


68. Can non-metals show photoelectric effect? [HOTS]

Answer/Explanation

Answer:
Explaination: Yes, when they are exposed to electromagnetic radiations of higher frequency.


69. A photosensitive surface emits photoelectrons when red light falls on it. Will the surface emit photoelectrons when blue light is incident on it? Give reason. [Foreign 2017]

Answer/Explanation

Answer:
Explaination:
Since condition for photoemission is \(\frac{h c}{\lambda} \geq \phi_{0}\) (work function) and λB < λR hence, surface will emit photoelectrons.


70. What happens to the wavelength of a photon after it collides with an electron?

Answer/Explanation

Answer:
Explaination: The wavelength of a photon increases.


71. State de Broglie hypothesis. [Delhi 2012]

Answer/Explanation

Answer:
Explaination:
“Particles of matter moving with a given velocity (momentum) can display wave-like properties”.
\(\lambda=\frac{h}{p}\)


72. Write the expression for the de Broglie wavelength associated with a charged particle having charge q and mass m, when it is accelerated by a potential V. [AI2013]

Answer/Explanation

Answer:
Explaination:
De Broglie wavelength associated with a charged particle when accelerated by a potential V is given by
\(\lambda=\frac{h}{p}=\frac{h}{\sqrt{2 m q V}}\)
where m = mass of charge particle and q = charge on the particle


73. A proton and an electron have same kinetic energy. Which one has smaller de Broglie wavelength and why? [AI 2012]

Answer/Explanation

Answer:
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 32


74. Show on a graph the variation of the de Broglie wavelength (λ) associated with an electron with the square root of accelerating potential (V). [Delhi 2019, Similar Panchkula 2019, Foreign 2012]
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 15

Answer/Explanation

Answer:
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 33


75. Write the relationship of de Broglie wavelength λ associated with a particle of mass m in terms of its kinetic energy E. [Delhi 2011C]

Answer/Explanation

Answer:
Explaination:
The required relation is given by \(\lambda=\frac{h}{\sqrt{2 m E}}\)


76. Name an experiment which shows wave nature of electrons. Which phenomenon was observed in this experiment using an electron beam?

Answer/Explanation

Answer:
Explaination:
Experiment: Davisson and Germer
Phenomenon: Diffraction


77. Two lines, A and B, in the plot given below show the variation of de Broglie wavelength, λ versus 1/√V, where V is the accelerating potential difference, for two particles carrying the same charge. Which one of two represents a particle of smaller mass?
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 16

Answer/Explanation

Answer:
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 34


78. The de Broglie wavelength of a particle of kinetic energy K is λ. What would be the wavelength of the particle, if its kinetic energy were K/4 [HOTS]

Answer/Explanation

Answer:
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 35


79. An electron and alpha particle have the same kinetic energy. How are the de Broglie wavelength associated with them related? [Similar Delhi 2019]

Answer/Explanation

Answer:
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 36


80. Two metals A and B have work functions 2 eV and 5 eV respectively. Which metal has lower threshold wavelength?

Answer/Explanation

Answer:
Explaination:
Metal with work function 5 eV has lower threshold wavelength, i.e. metal B.


81. Show graphically how the maximum kinetic energy of electrons emitted from a photosensitive surface varies with the frequency of incident radiations.

Answer/Explanation

Answer:
Explaination:
Physics MCQs for Class 12 with Answers Chapter 11 Dual Nature of Radiation and Matter 37


82. What is the charge on metal in the photoelectric experiment?

Answer/Explanation

Answer:
Explaination: It will possess positive charge as it has lost electrons.


83. What is the momentum of a photon of
(i) frequency v, and (ii) wavelength λ?

Answer/Explanation

Answer:
Explaination:
(i) Energy of photon
E = hv = mc²
∴ Momentum of a photon = mc = \(\frac{hv}{c}\)
(ii) The momentum of a photon of wavelength λ is p = \(\frac{h}{\lambda}\).
where h is the Planck’s constant.


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