Schrödinger wave equation - free particle, particle in a potential well, barrier penetration, probability interpretation, expectation values, eigenfunctions and eigenvalues, stationary states, wave packets, uncertainty principle - Question Bank

1. For a particle in a one-dimensional infinite potential well, the energy levels increase with:
A) Decreasing n
B) Increasing n
C) Constant n
D) The width of the well
2. The probability interpretation of the wave function was first proposed by:
A) Erwin Schrödinger
B) Werner Heisenberg
C) Max Born
D) Albert Einstein
3. Which of the following is NOT an eigenfunction of the momentum operator p̂ = -iħ d/dx in one dimension?
A) e^(ikx)
B) cos(kx)
C) e^(-ikx)
D) e^(i(kx + ωt))
4. If Δx = 0, then according to the uncertainty principle, Δp must be:
A) 0
B) Finite and positive
C) Infinite
D) Imaginary
5. The concept of a 'wave packet' is crucial for describing:
A) The instantaneous position of a particle
B) The spread of possible positions and momenta of a particle
C) The speed of light
D) The energy of a photon
6. What is the probability of finding a particle in an infinite potential well outside the well (from -∞ to 0 and L to ∞)?
A) 1
B) 0
C) 0.5
D) Depends on the energy
7. The Schrödinger equation is a relativistic equation.
A) True
B) False
C) Only for high energies
D) Only for particles with spin
8. What is the expectation value of the momentum for a particle in a stationary state of the infinite potential well?
A) Zero
B) Non-zero and dependent on n
C) ħ/L
D) h/L
9. For a particle in a one-dimensional infinite potential well, the wave functions are:
A) Orthogonal
B) Linear
C) Random
D) Constant
10. The 'barrier penetration' phenomenon is a direct consequence of:
A) Classical mechanics
B) The wave nature of particles and the uncertainty principle
C) Newton's laws of motion
D) Thermodynamics
11. What happens to the probability density |Ψ|² for a free particle described by a plane wave?
A) It is zero everywhere
B) It is localized
C) It is constant everywhere
D) It oscillates rapidly
12. If the wave function of a particle is Ψ(x), what is the probability of finding it between x and x+dx?
A) |Ψ(x)|² dx
B) Ψ(x) dx
C) Re(Ψ(x)) dx
D) Im(Ψ(x)) dx
13. The momentum operator in one dimension is given by:
A) -iħ d/dx
B) ħ d/dx
C) -ħ d/dx
D) iħ d/dx
14. For a particle in a finite potential well, the energy levels are:
A) Discrete and unbounded
B) Discrete and bounded
C) Continuous
D) Always zero
15. What is the physical significance of the imaginary unit 'i' in the time-dependent Schrödinger equation?
A) It ensures the wave function is real
B) It relates to the oscillatory nature of quantum phenomena
C) It indicates the particle's spin
D) It represents the potential energy
16. Consider a potential step V(x) = 0 for x < 0 and V(x) = V₀ for x > 0. If a particle with energy E > V₀ approaches from the left, what can happen?
A) Complete reflection
B) Complete transmission
C) Partial reflection and partial transmission
D) Tunneling only
17. The eigenfunctions of the Hamiltonian for a system are:
A) Always sinusoidal
B) The stationary states of the system
C) Always complex exponentials
D) Independent of the potential energy
18. If the potential energy V(x) = 0 for all x, the system describes a:
A) Harmonic oscillator
B) Free particle
C) Particle in a box
D) Hydrogen atom
19. The uncertainty relation between energy and time, ΔE Δt ≥ ħ/2, implies that:
A) Energy can be known precisely for any duration
B) Short-lived states have inherently uncertain energies
C) Time is quantized
D) Energy is always constant
20. A wave packet that is initially localized will tend to:
A) Become more localized over time
B) Spread out or disperse over time
C) Remain localized indefinitely
D) Collapse into a single point
21. What is the normalization condition for a wave function?
A) ∫ |Ψ|² dx = 1
B) ∫ Ψ dx = 0
C) ∫ Ψ* Ψ dx = 0
D) ∫ |Ψ|² dx = ∞
22. The expectation value of energy for a stationary state is:
A) Dependent on time
B) Equal to the eigenvalue E
C) Zero
D) Infinite
23. In quantum mechanics, the operator corresponding to position is simply multiplication by x, denoted as X.
A) True
B) False
C) Only for free particles
D) Only in one dimension
24. The probability of a particle tunneling through a barrier depends most strongly on:
A) The mass of the particle and the width and height of the barrier
B) The charge of the particle
C) The temperature of the system
D) The initial velocity of the particle
25. What is the probability density for a particle in the ground state of an infinite potential well (L=1)?
A) 2/L sin²(nπx/L)
B) 1/L
C) 2/L sin²(πx/L)
D) 2/L cos²(πx/L)
26. For a particle in a one-dimensional infinite potential well, the ground state energy (n=1) is:
A) 0
B) π²ħ²/2mL²
C) h²/8mL²
D) ħ²/2mL²
27. What is the wave function for a free particle moving in one dimension with momentum p?
A) Ψ(x) = A e^(ipx/ħ)
B) Ψ(x) = A sin(px/ħ)
C) Ψ(x) = A cos(px/ħ)
D) Ψ(x) = A
28. If a particle's momentum is known with very high precision, then its:
A) Position is known with very high precision
B) Position is known with very low precision
C) Energy is known with very high precision
D) Velocity is zero
29. A particle confined to a smaller region of space will have:
A) A smaller uncertainty in momentum
B) A larger uncertainty in momentum
C) No uncertainty in momentum
D) A constant momentum
30. Mathematically, the uncertainty principle for position and momentum is expressed as:
A) Δx Δp ≥ ħ/2
B) Δx Δp ≥ ħ
C) Δx ΔE ≥ ħ/2
D) Δt ΔE ≥ ħ
31. Heisenberg's Uncertainty Principle states that it is impossible to simultaneously know with perfect accuracy:
A) Position and velocity
B) Position and momentum
C) Energy and time
D) All of the above
32. What is the primary advantage of using a wave packet to describe a particle?
A) It allows for infinite precision in position measurement
B) It can represent a localized particle
C) It simplifies the calculation of energy levels
D) It eliminates the uncertainty principle
33. A wave packet is formed by the superposition of:
A) Plane waves with the same frequency
B) Plane waves with different frequencies and wavelengths
C) Standing waves
D) Harmonic oscillators
34. What are 'stationary states' in quantum mechanics?
A) States where the particle is always at rest
B) States whose probability density |Ψ|² is constant in time
C) States that decay exponentially over time
D) States that exhibit rapid oscillations in time
35. Solutions to the time-independent Schrödinger equation, HΨ = EΨ, yield:
A) Time-dependent wave functions
B) Eigenfunctions (stationary states) and eigenvalues (energy levels)
C) Probability densities only
D) Momentum values only
36. The time-independent Schrödinger equation is given by:
A) iħ ∂Ψ/∂t = HΨ
B) HΨ = EΨ
C) ∂Ψ/∂x = kΨ
D) ∂²Ψ/∂x² = -k²Ψ
37. What is an eigenvalue associated with an eigenfunction?
A) The function itself
B) The constant multiplier that the operator yields when acting on the eigenfunction
C) The integral of the eigenfunction
D) The derivative of the eigenfunction
38. What is an eigenfunction of an operator?
A) A function that is always zero
B) A function that, when acted upon by the operator, returns a constant multiple of itself
C) A function that changes sign when acted upon by the operator
D) A function that is orthogonal to all other functions
39. The expectation value of an observable 'A' is given by:
A) ∫ Ψ* A Ψ dx
B) ∫ Ψ A Ψ* dx
C) ∫ |Ψ|² A dx
D) ∫ Ψ* Ψ dx / A
40. What is an 'expectation value' in quantum mechanics?
A) The most likely value of a measurable quantity
B) The average value of a measurable quantity over many measurements
C) The minimum possible value of a measurable quantity
D) The maximum possible value of a measurable quantity
41. What is the physical interpretation of the wave function Ψ(x,t) in quantum mechanics (Born interpretation)?
A) It represents the amplitude of the wave
B) Its square, |Ψ(x,t)|², is the probability density of finding the particle at position x and time t
C) It is directly proportional to the particle's momentum
D) It describes the particle's velocity
42. The probability of finding a particle in a given region of space is proportional to:
A) The square of the wave function, |Ψ|²
B) The wave function, Ψ
C) The derivative of the wave function, dΨ/dx
D) The integral of the wave function, ∫Ψ dx
43. What is the name given to the phenomenon where a quantum particle can pass through a potential energy barrier even if its energy is less than the barrier height?
A) Quantum tunneling
B) Wave-particle duality
C) Superposition
D) Entanglement
44. What are the boundary conditions for the wave function of a particle in an infinite potential well from x=0 to x=L?
A) Ψ(0) = 0 and Ψ(L) = 0
B) dΨ/dx |_(x=0) = 0 and dΨ/dx |_(x=L) = 0
C) Ψ(0) = Ψ(L)
D) dΨ/dx |_(x=0) = dΨ/dx |_(x=L)
45. Consider a particle confined to a one-dimensional infinite potential well of width L. What are the allowed energy levels?
A) E_n = n²π²ħ²/2mL²
B) E_n = nπħ/L
C) E_n = nħ²/2mL²
D) E_n = n²h²/8mL²
46. What does the Hamiltonian operator (H) represent in the Schrödinger equation?
A) The momentum operator
B) The total energy operator
C) The potential energy operator
D) The kinetic energy operator
47. What is the time-dependent Schrödinger equation?
A) iħ ∂Ψ/∂t = HΨ
B) HΨ = EΨ
C) ∂Ψ/∂x = kΨ
D) ∂²Ψ/∂x² = -k²Ψ
48. For a free particle in quantum mechanics, what is the form of its wave function?
A) A localized wave packet
B) A plane wave
C) A standing wave
D) A decaying exponential
49. What is the fundamental equation describing the evolution of a quantum mechanical system's wave function over time?
A) Heisenberg's Uncertainty Principle
B) Schrödinger Equation
C) Bohr's Model
D) Maxwell's Equations
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