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.
Last updated
Read the Dawn of Modern Physics notesFree MDCAT chapter notes with key terms739 questions · page 4 of 37
- A. It does emit radiation
- B. Its size as compare to proton and neutron is very small
- C. No antiparticle of electron is present
- D. The velocity of electron must be very high according to uncertainty principle
Explanation: If an electron were confined inside a nucleus of extremely small size, the uncertainty principle would require a very large uncertainty in…
Correct answer: The velocity of electron must be very high according to uncertainty principle- A. Line spectrum of atoms
- B. Production of x-rays.
- C. Diffraction by crystalline solids
- D. Photoelectric effect
Explanation: Electron wave behaviour is demonstrated by electron diffraction from crystalline solids, where the regularly spaced atomic planes act like…
Correct answer: Diffraction by crystalline solids- A. Karl-Weins law
- B. Rayleigh-Jeans law
- C. Stephens law
- D. Plancks
Explanation: The Stefan-Boltzmann law states that the total energy radiated per unit area per unit time is proportional to T^4, where T is the absolute…
Correct answer: Stephens law- A. Property of matter and radiation
- B. Two-dimensional motion
- C. Emission of the certain wavelength
- D. Very high velocity
Explanation: The uncertainty in position and momentum is an intrinsic wave-particle property of matter and radiation, expressed by Δx Δp >= h/(4π).
Correct answer: Property of matter and radiation- A. Interference
- B. Polarization
- C. Electron diffraction
- D. Refraction
Explanation: The Davisson-Germer experiment produced diffraction of electrons by a nickel crystal, confirming that moving particles can have wave…
Correct answer: Electron diffraction- A. Ampere
- B. Plank
- C. Thomson
- D. Einstein
Explanation: Einstein introduced the term photon for a quantum, or packet, of electromagnetic radiation while explaining the photoelectric effect.
Correct answer: Einstein- A. shifts towards longer wavelength
- B. shifts towards shorter wavelength
- C. remain the same
- D. shifts towards longer as well as shorter wavelengths
Explanation: Wien's displacement law states λmax T = constant, so increasing the black-body temperature makes the wavelength of maximum intensity…
Correct answer: shifts towards shorter wavelength- A. equal to its rest mass
- B. double of its rest mass
- C. infinite
- D. zero
Explanation: Relativistic mass is often written m = m0/sqrt(1 - v^2/c^2), so as v approaches c, the denominator approaches zero and the mass tends to…
Correct answer: infinite- A. ∆E = h/m∆c(1-cosθ)
- B. ∆E . ∆t = h
- C. mc2 = hv
- D. Any of above
Explanation: The energy-time form of the uncertainty principle is ΔE Δt approximately equal to h/4π, or often written approximately as h in simplified…
Correct answer: ∆E . ∆t = h- A. greater than one meter
- B. less than one meter
- C. one meter
- D. a foolish question
Explanation: Length contraction gives L = L0 sqrt(1 - v^2/c^2), so an object moving rapidly relative to the observer is measured shorter than its…
Correct answer: less than one meter- A. 2.50 GWh
- B. 25.00 GWh
- C. 0.26 GWh
- D. 250 GWh
Explanation: Using mass-energy equivalence, E = mc2 = 0.001 kg x (3 x 10^8 m/s)2 = 9 x 10^13 J.
Correct answer: 25.00 GWh- A. Ec2
- B. E/c2
- C. E/c
- D. c2/E
Explanation: From E = mc2, dividing both sides by c2 gives m = E/c2, so relativistic mass is equivalent to E/c2.
Correct answer: E/c2- A. 1
- B. 2
- C. 3
- D. 4
Explanation: Fundamental science is commonly divided into three broad frontiers: the very small, the very large, and the very complex.
Correct answer: 3- A. Chemistry
- B. Astronomy
- C. Geology
- D. Biology
Explanation: Biology is a life science because it studies living organisms, whereas chemistry, astronomy and geology are traditionally grouped among…
Correct answer: Biology75. Which branch of science plays an important role in the development of technology and engineering ?
- A. Chemistry
- B. Physics
- C. Geology
- D. Biology
Explanation: Physics explains matter, energy, forces and their interactions, providing the principles used in machines, structures, electronics and…
Correct answer: Physics- A. Cloud chamber
- B. Linear accelerator
- C. A mass spectrograph
- D. Wilson cloud chamber
Explanation: A linear accelerator uses electric fields to accelerate charged nuclei or other particles to very high speeds.
Correct answer: Linear accelerator- A. Transport vibrations
- B. Transport signals
- C. Transport charge
- D. Transport impulses
Explanation: Conduction-band electrons have enough energy to move through the solid, so they carry electric charge and produce current.
Correct answer: Transport charge- A. Conduction band
- B. Valence band
- C. Forbidden band
- D. Empty band
Explanation: A conduction band is an allowed energy band that is empty or only partly occupied, allowing electrons to move into nearby empty energy…
Correct answer: Conduction band- A. Force corners
- B. Nine corners
- C. Eight corners
- D. Six corners
Explanation: A simple cubic unit cell has atoms at all eight corners, with each corner atom shared among eight neighbouring cells.
Correct answer: Eight corners- A. Cleavage
- B. Symmetry
- C. Isotropy
- D. Homogeneity
Explanation: Cleavage is the tendency of a crystal to split along definite planes or directions where bonding is relatively weaker.
Correct answer: Cleavage