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 34 of 37
- A. Elementary physics
- B. Article physics
- C. Ionic physics
- D. Plasma physics
Explanation: Option A : Elementary physics refers to the fundamental principles and laws of physics that describe the behaviour of matter and energy in…
Correct answer: Plasma physics- A. 1
- B. Less than 1
- C. Absolutely no
- D. None of these
Explanation: Option A : Things are not predicted with 1 precision. Option: B In a subatomic world, things can be predicted with less than 1 precision.
Correct answer: Less than 1- A. emits all radiation
- B. absorbs all radiation
- C. both a and b
- D. none of these
Explanation: A blackbody is defined as an ideal body that allows all incident radiation to pass into it (zero reflectance) and that absorbs internally…
Correct answer: both a and b- A. Newton's law
- B. Einstein's law
- C. Coulomb's law
- D. All of these options are correct
Explanation: Option A) Newton's law is incorrect because Newton's laws of motion deal with the behaviour of objects under the influence of external…
Correct answer: Einstein's law- A. Inversely proportional
- B. Directly proportional
- C. Equal to each other
- D. None of these options is correct
Explanation: Option A) Inversely proportional is not correct because the relationship between mass and energy is a direct proportion, as described by…
Correct answer: Directly proportional- A. emit
- B. absorb
- C. both a and b
- D. reflects
Explanation: Black Bodies are ideal entities that have the ability to absorb all forms of radiation that they come across.
Correct answer: both a and b- A. Newton's law
- B. Einstein law
- C. Coulomb law
- D. All of these
Explanation: Energy and Mass Are RelativeThe equation E = mc^2 states that the amount of energy possessed by an object is equal to its mass multiplied…
Correct answer: Einstein law- A. Particle Nature
- B. Wave Nature
- C. Dual Nature
- D. Transforms to Photon
Explanation: Correct Option: CThe electron exhibits both particle and wave-like properties, as described by the concept of dual nature in quantum…
Correct answer: Dual Nature- A. Particle nature
- B. Wave nature
- C. Dual nature
- D. It transforms to photon
Explanation: The electron is purely a dual nature when it's free. In quantum mechanics, electrons can behave as both particles and waves, depending on…
Correct answer: Dual nature- A. Bohr
- B. Einstein
- C. Rutherford
- D. None of these options is correct
Explanation: Einstein gave the concept of work function.
Correct answer: Einstein- A. Wave nature
- B. Particle nature
- C. Dual nature
- D. It never moves when in bound state
Explanation: The bound state electron has wave-particle duality, meaning it exhibits both particle-like and wave-like properties.
Correct answer: Dual nature- A. No light will reach the surface
- B. Extra light will reach the surface
- C. Nothing will happen
- D. Some light will reflect, and some will be absorbed
Explanation: If Earth's clouds were perfect black bodies, then they would absorb the sunlight falling on them and radiate that energy as heat.
Correct answer: No light will reach the surface- A. Red
- B. Green
- C. Blue
- D. Black
Explanation: A hot body emits radiations, having perceived wavelengths changing from infrared to red, and then from red to orange, and so on.
Correct answer: Red- A. λ= hxp
- B. λ=h/p
- C. λ=h+p
- D. λ=h-p
Explanation: λ= h/p This equation relating the momentum of a particle with its wavelength is de Broglie equation and the wavelength calculated using…
Correct answer: λ=h/p- A. Stimulated emission
- B. Spontaneous emission
- C. Absorption
- D. All of these
Explanation: The emission of LASERs requires all three of the above-mentioned phenomena.
Correct answer: All of these- A. Increase.
- B. Completely diminishes.
- C. Reduces to half.
- D. Remains unchanged.
Explanation: The requirement for a photon to carry out pair production is a minimum energy level of 1.02 MeV, if the energy level increases the…
Correct answer: Increase.- A. Infrared.
- B. Ultraviolet.
- C. Visible.
- D. Green.
Explanation: In photocell cesium, coated oxidised silver cathode emits electrons for infrared light.
Correct answer: Infrared.- A. Low
- B. High
- C. Intermediate
- D. Both A and C
Explanation: Energy will be emitted when electrons jump from higher energy levels to lower energy levels.
Correct answer: High- A. hf - ϕ = ½ mv2
- B. E = hc2
- C. E = mc2
- D. hf = ½ mv2
Explanation: Explanation:Einstein's photoelectric equation states that the maximum energy of a photoelectron is equal to the difference between the…
Correct answer: hf - ϕ = ½ mv2- A. 1.43 x 10^-11 m
- B. 2.43 x 10^-12 m
- C. 2.56 x 10^-12 m
- D. 3.46 x 10^-6 m
Explanation: Explanation: This value is a constant and is given as: = h / moc = 6.63 × 10-23 / (9.1093837015 × 10-31kg) (3× 108 ms-1) = 2.43 × 10-12m
Correct answer: 2.43 x 10^-12 m