Summary & 50 MCQs with Answers
This chapter explains the dual nature of radiation and matter, covering photons, photoelectric effect, de Broglie wavelength, matter waves, and electron behavior. It introduces quantum theory, Planck’s constant, and experiments confirming wave-particle duality.
1. Photon energy is given by:
A) E = hν ✅
B) E = mc²
C) E = 1/2 mv²
D) E = λ/c
2. Planck’s constant has value approximately:
A) 6.626 × 10⁻³⁴ Js ✅
B) 3 × 10⁸ m/s
C) 1.6 × 10⁻¹⁹ C
D) 9.11 × 10⁻³¹ kg
3. Photoelectric effect demonstrates:
A) Particle nature of light ✅
B) Wave nature of light
C) Continuous energy emission
D) Nuclear reaction
4. Threshold frequency is:
A) Minimum frequency to emit photoelectron ✅
B) Maximum frequency absorbed
C) Any frequency
D) Related to electron spin
5. de Broglie wavelength is given by:
A) λ = h/p ✅
B) λ = c/f
C) λ = v/f
D) λ = 1/√p
6. Maximum kinetic energy of photoelectron is given by:
A) K_max = hν - Φ ✅
B) K_max = h/ν
C> K_max = Φ - hν
D> K_max = mv²/2
7. Work function (Φ) depends on:
A) Material of surface ✅
B) Frequency of light
C) Intensity of light
D) Distance from source
8. Einstein explained photoelectric effect using:
A) Photon theory of light ✅
B) Wave theory of light
C) Newton’s laws
D) Rutherford model
9. Photoelectric current depends on:
A) Light intensity ✅
B) Frequency alone
C) Work function alone
D) Material temperature only
10. Stopping potential is:
A) Minimum voltage to stop photoelectrons ✅
B) Voltage to accelerate electrons
C) Threshold frequency
D) Kinetic energy of electron
11. Electron behaves as wave as per:
A) de Broglie hypothesis ✅
B) Planck’s theory
C) Newton’s laws
D) Einstein relativity
12. Matter wave associated with electron confirmed by:
A) Davisson-Germer experiment ✅
B) Photoelectric effect
C> Compton effect
D> Rutherford scattering
13. de Broglie wavelength of moving particle:
A) λ = h/mv ✅
B) λ = c/f
C) λ = v/f
D) λ = hν
14. Photon momentum is given by:
A) p = h/λ ✅
B) p = mv
C) p = E/c²
D) p = mc
15. Compton effect confirms:
A) Particle nature of light ✅
B) Wave nature of light
C) Duality of matter only
D) Nuclear fission
16. Wavelength change in Compton effect depends on:
A) Scattering angle ✅
B) Light intensity
C> Electron mass only
D> Source distance
17. de Broglie wavelength decreases when:
A) Particle velocity increases ✅
B) Particle velocity decreases
C> Mass decreases
D> Planck’s constant increases
18. Photoelectric effect is not explained by:
A) Wave theory of light ✅
B) Photon theory
C> Einstein equation
D> Quantum theory
19. Kinetic energy of photoelectron depends on:
A) Frequency of incident light ✅
B) Intensity only
C> Material only
D> Distance from source
20. Photon has:
A) Zero rest mass ✅
B) Mass of electron
C> Mass of proton
D> Non-zero rest mass
21. Intensity of light affects:
A) Number of photoelectrons ✅
B) Kinetic energy
C> Threshold frequency
D> Work function
22. Threshold frequency depends on:
A) Material ✅
B) Light intensity
C> Distance
D> Wavelength only
23. Photoelectric effect shows:
A) Light consists of photons ✅
B) Continuous wave nature
C> Interference only
D> Reflection only
24. Einstein’s photoelectric equation is:
A) K_max = hν - Φ ✅
B) E = mc²
C> λ = h/p
D> E = hν
25. Dual nature refers to:
A) Particle + Wave behavior ✅
B) Particle only
C> Wave only
D> Neither
26. Davisson-Germer experiment observed:
A) Electron diffraction ✅
B) Photon absorption
C> Nuclear decay
D> Radioactivity
27. Matter waves are:
A) Associated with moving particles ✅
B) Only light waves
C> Sound waves
D> Static waves
28. Electron diffraction proves:
A) Wave nature of matter ✅
B) Particle nature only
C> Light waves
D> Magnetic fields
29. de Broglie wavelength is observable for:
A) Small mass particles ✅
B) Macroscopic objects
C> Any object
D> Only photons
30. Energy of photon is proportional to:
A) Frequency ✅
B) Wavelength
C> Mass
D> Amplitude
31. Light intensity affects:
A) Number of emitted electrons ✅
B) Energy of electrons
C> Wavelength
D> Frequency
32. Kinetic energy of photoelectron depends on:
A) Frequency above threshold ✅
B) Intensity only
C> Work function only
D> None
33. Electron diffraction is evidence of:
A) Wave nature of electrons ✅
B) Particle nature only
C> Light waves
D> Nuclear decay
34. Photoelectric effect proves:
A) Particle nature of light ✅
B) Wave nature only
C> Matter waves
D> Interference phenomenon
35. de Broglie wavelength increases when:
A) Particle velocity decreases ✅
B) Mass increases
C> Velocity increases
D> Energy increases
36. Maximum kinetic energy of photoelectron is independent of:
A) Intensity of light ✅
B) Frequency above threshold
C> Work function
D> Photon energy
37. Stopping potential is measured in:
A) Volts ✅
B) Joules
C> Electron volts
D> Watts
38. Wavelength of matter wave depends on:
A) Particle momentum ✅
B) Particle mass only
C> Speed of light
D> Planck’s constant only
39. Compton shift increases with:
A) Scattering angle ✅
B) Photon intensity
C> Electron mass decrease
D> Distance from source
40. Photon carries momentum but has:
A) Zero rest mass ✅
B) Mass of electron
C> Mass of proton
D> Non-zero rest mass
41. Number of emitted electrons is proportional to:
A) Light intensity ✅
B) Frequency above threshold only
C> Work function
D> Stopping potential
42. Work function is:
A) Minimum energy to remove electron ✅
B) Maximum kinetic energy
C> Photon energy
D> Threshold voltage
43. Kinetic energy of emitted electron is zero when:
A) Light frequency equals threshold ✅
B) Light intensity is zero
C> Work function is zero
D> Stopping potential is negative
44. Electron behaves as particle in:
A) Photoelectric effect ✅
B) Electron diffraction
C> Interference
D> Refraction
45. Wave nature of electron is prominent for:
A) Small mass and high velocity ✅
B) Large mass objects
C> Stationary objects
D> Photons
46. Energy of photon is inversely proportional to:
A) Wavelength ✅
B) Frequency
C> Momentum
D> Planck’s constant
47. Kinetic energy of photoelectron is maximum when:
A) Light frequency is maximum ✅
B) Intensity is minimum
C> Work function is maximum
D> Photon energy is zero
48. Wave-particle duality is observed in:
A) Light and electrons ✅
B) Only light
C> Only electrons
D> Sound waves
49. de Broglie hypothesis unifies:
A) Classical and quantum behavior ✅
B) Newtonian and relativistic mechanics
C> Wave and sound theories
D> None
50. The dual nature of matter and radiation was confirmed by:
A) Photoelectric and electron diffraction experiments ✅
B) Only Rutherford experiment
C> Only Bohr model
D> Only Thomson experiment