Free Dawn of Modern Physics MCQs with Answers
739 Dawn of Modern Physics MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Classical physics cannot explain blackbody radiation and related observations, leading to Planck’s quantum theory, in which energy is emitted or absorbed in discrete packets. Photons provide the particle model of light, with energy and momentum linked to frequency and wavelength, including the photoelectric effect and its threshold frequency.
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Read the Dawn of Modern Physics notesFree MDCAT chapter notes with key terms739 questions · page 20 of 37
- A. 6.63 x 10^-35
- B. 6.63 x 10^-34
- C. 6.63 x 10^-33
- D. 6.63 x 10^-32
Explanation: .de Broglie reasoned that matter also can show Wave-particle duality just like light, since light can behave both as a wave (it can be…
Correct answer: 6.63 x 10^-33- A. No photoelectrons are produced
- B. No photoelectric effect is observed
- C. No photo electric current is produced
- D. All of these options are correct
Explanation: no photoelectric current is produced although photoelectrons are emitted they do not move or do not have kinetic energy as, hv = W ( work…
Correct answer: No photo electric current is produced383. If we use a light of photons having energy 2.4 eV then the stopping potential required will be:
- A. 2.4 V
- B. 2.6 V
- C. 2.5 V
- D. 0 V
Explanation: The formula for stopping potential is: K.Emax=leV0l Rearranging: V0= K.Emax/e =V0= 2.4ev/e V0=2.4 V answer!
Correct answer: 2.4 V- A. 6.63 × 10−22 kg m s−1
- B. 6.63 × 10−27 kg m s−1
- C. 6.63 × 10−31 kg m s−1
- D. 6.63 × 10−34 kg m s−1
Explanation: We know that,λ= h / pp=6.26×10 −22 kgm/s
Correct answer: 6.63 × 10−22 kg m s−1- A. Frequency of incident light
- B. Intensity of incident light
- C. Nature of cathode surface
- D. Wavelength of light
Explanation: The working of a photocell can be explained by the photoelectric effect.•The photoelectrons which are released when a beam of light falls…
Correct answer: Intensity of incident light- A. Ordinary water
- B. Heavy water
- C. Lead
- D. Aluminum
Explanation: Gamma rays are known to have maximum penetration they can penetrate several metals.
Correct answer: Lead- A. Interference of light
- B. Refraction of light
- C. Polarization of light
- D. Dispersion of light
Explanation: A light wave is an electromagnetic wave which travels through the vacuum of outer space and transparent materials like glass.
Correct answer: Polarization of light- A. Intensity of radiation
- B. Wavelength
- C. Frequency of radiation
- D. Both wavelength and intensity
Explanation: The energy of incident light is directly proportional to its frequency.
Correct answer: Frequency of radiation- A. 8 x 10^14 Hz
- B. 3.2 x 10^15 Hz
- C. 4.8 x 10^15 Hz
- D. 6.4 x 10^15 Hz
Explanation: The correct option is A.To calculate the minimum frequency of light required to eject an electron from a surface, we need to use the…
Correct answer: 8 x 10^14 Hz- A. Rest mass of photon
- B. Wavelength of photon
- C. Light speed
- D. Momentum of photon
Explanation: Particle nature and wave nature of electromagnetic waves and electrons is called dual nature or wave particle dualism.
Correct answer: Momentum of photon- A. Momentum
- B. Frequency
- C. Mass
- D. Energy
Explanation: In quantum physics, wave-particle duality states that any particle or quantum phenomenon can be represented as either a particle or a…
Correct answer: Mass- A. Three Times
- B. Sixteen Times
- C. Four Times
- D. Same
Explanation: The energy radiated per unit area by a black body is governed by Stefan's law.
Correct answer: Sixteen Times- A. T-2
- B. T4
- C. T-4
- D. None of these
Explanation: By the Stefan-Boltzmann Law, for a black body, the amount of heat radiated per unit area is directly proportional to the fourth power of…
Correct answer: T4- A. To propagate
- B. Stay at rest
- C. Mass less objects
- D. Charged object
Explanation: Radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium.
Correct answer: To propagate- A. Same direction
- B. Opposite direction
- C. Perpendicular position
- D. Remain stationary
Explanation: Annihilation refers to a process in which a particle and its corresponding antiparticle come into contact and mutually annihilate…
Correct answer: Opposite direction- A. 10V
- B. 8V
- C. 5V
- D. 4V
Explanation: The required equation is given as:Stopping voltage = Kmax/e.Kmax/e=5.0eV/eKmax/e = 5.0 VTherefore, the stopping potential = 5 V.
Correct answer: 5V- A. Continuous
- B. Discrete
- C. Band
- D. Line
Explanation: A black body is an idealized object that absorbs all electromagnetic radiation it comes in contact with.
Correct answer: Continuous- A. Diffraction
- B. Interference
- C. Photoelectric Effect
- D. Polarization
Explanation: The correct answer is the Photoelectric Effect. This phenomenon cannot be adequately described by the wave theory of light alone because…
Correct answer: Photoelectric Effect- A. I only
- B. II only
- C. III only
- D. I and II only
- E. I, II and III
Explanation: Explanation:i) Postulate I states that a finite volume of gas is composed of a very large number of molecules.
Correct answer: I, II and III- A. I only
- B. II only
- C. I and II only
- D. None of the above
Explanation: Einstein's special theory of relativity states that the same laws of physics hold true in all inertial reference frames and that the speed…
Correct answer: I and II only