1Which experiment historically established the particle nature of light?
A.Interference
B.Diffraction
C.Photoelectric Effect
D.Polarization
Correct Answer: Photoelectric Effect
Explanation:Interference, diffraction, and polarization demonstrate the wave nature of light, while the Photoelectric effect demonstrates the particle (quantum) nature of light.
Incorrect! Try again.
2According to Planck's hypothesis, energy is emitted or absorbed in discrete packets called quanta. The energy of a quantum is given by:
A.
B.
C.
D.
Correct Answer:
Explanation:Planck's law states that the energy of a photon is proportional to its frequency, given by , where is Planck's constant.
Incorrect! Try again.
3In the photoelectric effect, the minimum energy required to remove an electron from the surface of a metal is called:
A.Kinetic Energy
B.Potential Energy
C.Stopping Potential
D.Work Function
Correct Answer: Work Function
Explanation:The Work Function () is the minimum amount of energy required by an electron to escape from a metal surface.
Incorrect! Try again.
4The Einstein's photoelectric equation is given by (where is maximum kinetic energy, is frequency, and is work function):
A.
B.
C.
D.
Correct Answer:
Explanation:Einstein's photoelectric equation states that the maximum kinetic energy of the emitted electron is the difference between the photon's energy () and the work function ().
Incorrect! Try again.
5The de Broglie wavelength associated with a particle of momentum is given by:
A.
B.
C.
D.
Correct Answer:
Explanation:According to the de Broglie hypothesis, the wavelength of matter waves is inversely proportional to momentum: .
Incorrect! Try again.
6If the velocity of a particle is doubled, its de Broglie wavelength will:
A.Double
B.Remain the same
C.Become half
D.Become four times
Correct Answer: Become half
Explanation:Since , wavelength is inversely proportional to velocity. If doubles, becomes half.
Incorrect! Try again.
7The de Broglie wavelength of an electron accelerated through a potential difference of volts is approximately given by:
A.
B.
C.
D.
Correct Answer:
Explanation:Substituting the constants , , and into , we get .
Incorrect! Try again.
8Which of the following bodies will have the shortest de Broglie wavelength if they all move with the same velocity?
A.Electron
B.Proton
C.Neutron
D.Alpha particle
Correct Answer: Alpha particle
Explanation:. For constant velocity, . The alpha particle has the largest mass among the options, so it has the shortest wavelength.
Incorrect! Try again.
9The de Broglie wavelength of a gas molecule at absolute temperature is given by:
A.
B.
C.
D.
Correct Answer:
Explanation:The kinetic energy of a gas molecule is . Substituting into , we get .
Incorrect! Try again.
10The Heisenberg Uncertainty Principle states that the product of uncertainties in position () and momentum () is always:
A.
B.
C.
D.
Correct Answer:
Explanation:Heisenberg's Uncertainty Principle states that it is impossible to measure both position and momentum simultaneously with arbitrary precision, with the limit .
Incorrect! Try again.
11Why is the wave nature of a moving cricket ball not observed in daily life?
A.Its velocity is too high
B.Its mass is too large, making negligible
C.It is not a charged particle
D.It does not satisfy Planck's law
Correct Answer: Its mass is too large, making negligible
Explanation:Because , the large mass of macroscopic objects leads to an extremely small wavelength that is undetectable.
Correct Answer: Electrons cannot exist inside the nucleus
Explanation:If an electron were confined to the nucleus (size m), the uncertainty in velocity would exceed the speed of light (or require impossibly high energy), which is physically impossible.
Incorrect! Try again.
13Another form of Heisenberg's uncertainty principle relates Energy () and Time () as:
A.
B.
C.
D.
Correct Answer:
Explanation:The uncertainty principle also applies to the measurement of energy and the time duration of the measurement.
Incorrect! Try again.
14The velocity with which the envelope of a wave packet moves is called:
A.Phase velocity
B.Group velocity
C.Light velocity
D.Sound velocity
Correct Answer: Group velocity
Explanation:The group velocity () represents the velocity of the wave packet (envelope) and corresponds to the velocity of the particle.
Incorrect! Try again.
15The phase velocity () is given by the relation:
A.
B.
C.
D.
Correct Answer:
Explanation:Phase velocity is the rate at which the phase of the wave propagates in space, defined as ratio of angular frequency to wave number.
Incorrect! Try again.
16For a non-relativistic material particle, the relation between group velocity () and particle velocity () is:
A.
B.
C.
D.
Correct Answer:
Explanation:The group velocity of the matter wave associated with a moving particle is equal to the classical velocity of that particle.
Incorrect! Try again.
17The phase velocity of matter waves associated with a particle moving with velocity is:
A.
B.
C.
D.Zero
Correct Answer:
Explanation:Using relativity, . Since , the phase velocity .
Incorrect! Try again.
18In a non-dispersive medium, the relationship between phase velocity () and group velocity () is:
A.
B.
C.
D.
Correct Answer:
Explanation:In a non-dispersive medium, velocity is independent of wavelength, so the phase velocity and group velocity are equal.
Incorrect! Try again.
19The wave function in quantum mechanics represents:
A.The exact position of the particle
B.The probability amplitude
C.The energy of the particle
D.The momentum of the particle
Correct Answer: The probability amplitude
Explanation: itself has no direct physical meaning but is the probability amplitude. Its square modulus represents probability density.
Incorrect! Try again.
20The quantity represents:
A.Charge density
B.Probability density
C.Mass density
D.Energy density
Correct Answer: Probability density
Explanation:According to Max Born's interpretation, (or ) represents the probability of finding the particle per unit volume (probability density).
Incorrect! Try again.
21For a wave function to be well-behaved, it must be:
A.Finite, continuous, and single-valued
B.Infinite, discontinuous, and multi-valued
C.Zero everywhere
D.Real and positive
Correct Answer: Finite, continuous, and single-valued
Explanation:To be physically meaningful, must be finite (normalizable), continuous (for momentum definition), and single-valued (unique probability).
Incorrect! Try again.
22The normalization condition for a wave function over all space is:
A.
B.
C.
D.
Correct Answer:
Explanation:Normalization ensures that the total probability of finding the particle somewhere in the entire universe is 1 (100%).
Incorrect! Try again.
23The operator for momentum () in one dimension is:
A.
B.
C.
D.
Correct Answer:
Explanation:In quantum mechanics, the momentum operator corresponds to the spatial derivative multiplied by .
Incorrect! Try again.
24The operator for total energy (Hamiltonian ) in the time-independent Schrodinger equation is:
A.
B.
C.
D.
Correct Answer:
Explanation:The Hamiltonian is the sum of Kinetic Energy operator () and Potential Energy operator ().
Incorrect! Try again.
25Schrodinger's time-independent wave equation in one dimension is:
A.
B.
C.
D.
Correct Answer:
Explanation:This is the standard form derived from , where kinetic energy is expressed as a second derivative.
Incorrect! Try again.
26For a particle in a one-dimensional box of length with infinite potential walls, the potential inside the box () is:
A.
B.$0$
C.
D.
Correct Answer: $0$
Explanation:The 'Particle in a Box' model assumes a free particle inside the box, meaning potential energy is zero inside and infinite outside.
Incorrect! Try again.
27The wave function for a particle in a 1D box of width is given by (where is an integer):
A.
B.
C.
D.
Correct Answer:
Explanation:Solving Schrodinger's equation with boundary conditions yields sine functions normalized by .
Incorrect! Try again.
28The energy eigenvalues for a particle in a 1D box of length are given by:
A.
B.
C.
D.
Correct Answer:
Explanation:Derived from and . Using instead of , .
Incorrect! Try again.
29The lowest possible energy (Zero Point Energy) for a particle in a box corresponds to:
A.
B.
C.
D.
Correct Answer:
Explanation:The quantum number cannot be zero (as would be zero everywhere), so the lowest state is .
Incorrect! Try again.
30Which of the following statements is true for a particle in a box?
A.Energy levels are continuous
B.Energy levels are discrete (quantized)
C.The particle can be at rest ()
D.The particle can exist outside the box
Correct Answer: Energy levels are discrete (quantized)
Explanation:Confinement of the wave leads to standing waves, which allows only specific (discrete) energy values.
Incorrect! Try again.
31The spacing between energy levels for a particle in a box:
A.Decreases as increases
B.Remains constant
C.Increases as increases
D.Varies randomly
Correct Answer: Increases as increases
Explanation:Since , the gap . The spacing increases with .
Incorrect! Try again.
32In the Quantum Tunneling effect, a particle can cross a potential barrier even if:
A.Its Total Energy () is less than the Barrier Height ()
B.
C.
D.The barrier width is infinite
Correct Answer: Its Total Energy () is less than the Barrier Height ()
Explanation:Classically impossible, quantum mechanics allows a non-zero probability of finding a particle on the other side of a barrier where .
Incorrect! Try again.
33The probability of tunneling decreases exponentially with:
A.Decreasing barrier width
B.Increasing barrier width and height
C.Decreasing particle mass
D.Increasing particle energy
Correct Answer: Increasing barrier width and height
Explanation:The transmission coefficient . Increasing the width or the barrier height (which increases ) drastically reduces probability.
Incorrect! Try again.
34Which device works on the principle of quantum tunneling?
Explanation:Compton scattering demonstrates that photons carry momentum and collide with electrons like particles.
Incorrect! Try again.
37The Davisson-Germer experiment confirmed the:
A.Particle nature of electrons
B.Wave nature of electrons
C.Speed of light
D.Charge of an electron
Correct Answer: Wave nature of electrons
Explanation:They observed diffraction patterns when electrons were scattered off a nickel crystal, confirming de Broglie's hypothesis.
Incorrect! Try again.
38If the size of the box () is doubled, the ground state energy of the particle becomes:
A.Double
B.Half
C.Four times
D.One-fourth
Correct Answer: One-fourth
Explanation:. If becomes , energy becomes , which is 1/4th the original.
Incorrect! Try again.
39In the time-dependent Schrodinger equation , the energy operator corresponds to:
A.
B.
C.
D.
Correct Answer:
Explanation:The total energy operator in time-dependent QM is .
Incorrect! Try again.
40A 'node' in a wave function is a point where:
A.Probability is maximum
B.Probability is zero
C.Potential energy is zero
D.Kinetic energy is zero
Correct Answer: Probability is zero
Explanation:Nodes are points where the wave function crosses zero, meaning the probability of finding the particle there is zero.
Incorrect! Try again.
41How many nodes (excluding boundaries) does the -th state wave function of a particle in a box have?
A.
B.
C.
D.
Correct Answer:
Explanation:For (ground state), there are 0 nodes. For , there is 1 node. In general, nodes.
Incorrect! Try again.
42Two wave functions and are said to be orthogonal if:
A. for
B. for
C.
D.They have the same energy
Correct Answer: for
Explanation:Orthogonality means the overlap integral between two different states is zero.
Incorrect! Try again.
43The failure of classical mechanics to explain the spectral distribution of blackbody radiation at short wavelengths is known as:
A.Infrared catastrophe
B.Ultraviolet catastrophe
C.Compton shift
D.Stark effect
Correct Answer: Ultraviolet catastrophe
Explanation:Classical Rayleigh-Jeans law predicted infinite energy at UV wavelengths, which contradicted experimental results.
Incorrect! Try again.
44In the macroscopic limit (large quantum numbers), quantum mechanics results approach classical mechanics results. This is known as:
A.Correspondence Principle
B.Uncertainty Principle
C.Exclusion Principle
D.Superposition Principle
Correct Answer: Correspondence Principle
Explanation:Niels Bohr's Correspondence Principle states that for large quantum numbers, quantum physics reduces to classical physics.
Incorrect! Try again.
45The momentum of a photon of frequency is:
A.
B.
C.
D.
Correct Answer:
Explanation:For a photon, and , so .
Incorrect! Try again.
46If the uncertainty in position of a particle is zero, the uncertainty in its momentum is:
A.Zero
B.Infinite
C.
D.Finite but small
Correct Answer: Infinite
Explanation:Since , if , then .
Incorrect! Try again.
47The stopping potential in a photoelectric experiment depends on:
A.Intensity of incident light
B.Frequency of incident light
C.Distance of light source
D.Time of irradiation
Correct Answer: Frequency of incident light
Explanation:Stopping potential is a measure of maximum kinetic energy, which depends on the photon energy (frequency), not intensity.
Incorrect! Try again.
48Increasing the intensity of incident light in a photoelectric experiment increases:
A.Kinetic energy of electrons
B.Stopping potential
C.Number of photoelectrons emitted
D.Work function
Correct Answer: Number of photoelectrons emitted
Explanation:Intensity corresponds to the number of photons. More photons release more electrons (current), but do not increase individual electron energy.
Incorrect! Try again.
49Matter waves are:
A.Electromagnetic waves
B.Mechanical waves
C.Probability waves
D.Transverse waves
Correct Answer: Probability waves
Explanation:Matter waves are not physical waves like sound or light (EM), but represent the probability distribution of a particle.
Incorrect! Try again.
50The wavelength of a electron is approximately:
A.
B.
C.
D.
Correct Answer:
Explanation:Using . . .
Incorrect! Try again.
Give Feedback
Help us improve by sharing your thoughts or reporting issues.