The concept of the dual nature of radiation and matter is a cornerstone of modern physics, bridging classical and quantum theories. It reveals the intriguing duality of light and matter, where they exhibit both particle-like and wave-like properties under different circumstances. This duality is fundamental to understanding phenomena like the photoelectric effect, diffraction, and interference.
The wave-particle duality of light was first explored through experiments like Young’s double-slit experiment, which demonstrated light’s wave nature. On the other hand, Einstein’s explanation of the photoelectric effect highlighted light’s particle-like behavior, where photons, the quanta of light, transfer energy to electrons, enabling their emission. This pivotal discovery earned Einstein the Nobel Prize and established the foundation of quantum mechanics.
The duality extends to matter, as explained by Louis de Broglie. He proposed that particles, such as electrons, also possess wave-like characteristics, described by the de Broglie wavelength. This was experimentally verified by the Davisson-Germer experiment, which showed electron diffraction, a phenomenon previously attributed only to waves.
This topic is vital for Class 12 Physics students as it builds a deeper understanding of the quantum world and its governing principles. Mastering this concept enables students to analyze practical applications, such as electron microscopes, X-ray diffraction, and semiconductor technologies.
MCQs on this topic help reinforce critical concepts and enhance problem-solving skills. Questions often focus on phenomena like the photoelectric effect, the relationship between energy, frequency, and wavelength, as well as the implications of de Broglie’s hypothesis. By practicing these MCQs, students can prepare effectively for board exams and competitive tests like JEE and NEET, ensuring a strong grasp of this fascinating domain of physics.
Class 12 Dual Nature of Radiation & Matter MCQs
In which of the following is electron emission not observed?
(a) Photoelectric Emission
(b) Thermionic Emission
(c) Secondary Emission
(d) X-Ray Emission
Answer: (d) X-Ray Emission
Explanation: Electrons are not emitted during X-Ray Emission.
What affects the kinetic energy of electrons emitted when light hits a metal surface?
(a) Frequency of light
(b) Intensity of light
(c) Speed of light
(d) Irregular variations
Answer: (a) Frequency of light
Explanation: The kinetic energy of electrons depends on the light’s frequency.
What does a photoelectric cell do?
(a) Converts light energy into electrical energy
(b) Converts electrical energy into light
(c) Stores light energy
(d) Stores electricity
Answer: (a) Converts light energy into electrical energy
Do Check: NCERT Solutions for Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter
What are cathode rays made of?
(a) Electrons
(b) Protons
(c) Photons
(d) Alpha particles
Answer: (a) Electrons
Who proposed the quantization of electric charge?
(a) J.J. Thomson
(b) William Crookes
(c) R.A. Millikan
(d) Wilhelm Hallwachs
Answer: (c) R.A. Millikan
Which metal is not sensitive to visible light?
(a) Rubidium
(b) Sodium
(c) Caesium
(d) Cadmium
Answer: (d) Cadmium
Explanation: Cadmium responds to ultraviolet light, not visible light.
What does the wave theory of light fail to explain?
(a) Diffraction
(b) Photocurrent
(c) Polarization
(d) Interference
Answer: (b) Photocurrent
Explanation: Wave theory cannot explain the photoelectric effect, which requires quantum theory.
Photons are deflected by:
(a) Magnetic field
(b) Electric field
(c) Electromagnetic field
(d) None of the above
Answer: (d) None of the above
Explanation: Photons are not deflected by electric or magnetic fields.
What law is the photoelectric effect based on?
(a) Conservation of energy
(b) Conservation of momentum
(c) Conservation of mass
(d) Conservation of angular momentum
Answer: (a) Conservation of energy
What does a photon lack?
(a) Energy
(b) Momentum
(c) Rest mass
(d) Frequency
Answer: (c) Rest mass
What happens when light exceeds a certain threshold frequency?
(a) Power increases
(b) Wavelength decreases
(c) Photoelectric emission occurs
(d) Intensity increases
Answer: (c) Photoelectric emission occurs
Do Check: 5 Toughest and Easiest Chapters in CBSE Class 12 Physics
Which radiation can emit photoelectrons upon striking a metal?
(a) UV Radiation
(b) Infrared Radiation
(c) Radio Waves
(d) Microwaves
Answer: (a) UV Radiation
Explanation: UV light has sufficient energy to cause photoelectric emission.
The work function of a metal is:
(a) Minimum current needed to eject an electron
(b) Maximum frequency needed to eject an electron
(c) Least energy required to eject an electron
(d) None of the above
Answer: (c) Least energy required to eject an electron
A metal’s work function depends on:
(a) Its surface properties
(b) Its dimensions
(c) Its abundance
(d) None of the above
Answer: (a) Its surface properties
What doesn’t affect the photoelectric current?
(a) Incident light intensity
(b) Frequency of light above the threshold
(c) Stopping potential
(d) Work function of the metal
Answer: (c) Stopping potential
Which phenomenon is explained by the photoelectric effect?
(a) Wave nature of light
(b) Particle nature of light
(c) Both wave and particle nature
(d) None of the above
Answer: (b) Particle nature of light
What is the least energy required to eject an electron from a metal surface called?
(a) Atomic energy
(b) Work function
(c) Electrical energy
(d) Mechanical energy
Answer: (b) Work function
