ECEN 370 Exam 1 Study guide
questions well answered
Explain the particle model for an electron - correct answer ✔✔ The particle model for an
electron considers it as a point particle with a definite mass, charge, and spin. It can be localized
in space and follows classical Newtonian mechanics under certain conditions.
Explain the wave model for an electron - correct answer ✔✔ The wave model for an electron
describes it as a wave that is spread out over space, having wave-like properties such as
interference and diffraction. The wavefunction describes the probability distribution of an
electron's position.
Define in words the concepts of mean free path, mean free time, drift mobility, and drift
velocity. - correct answer ✔✔ Mean free path is the average distance a particle travels between
collisions. Mean free time is the average time between collisions. Drift mobility is the average
drift velocity of carriers per unit electric field in a semiconductor. Drift velocity is the average
velocity of a particle when moving in one direction, averaged over a time interval.
Write the equation for the Lorentz Force and explain what it describes - correct answer ✔✔ F =
qE + qv x B. The Lorentz Force describes the force experienced by a charged particle in an
electromagnetic field, composed of electric (qE) and magnetic (qv x B) force components.
Explain in words the Hall Effect - correct answer ✔✔ The Hall Effect refers to the production of a
voltage (Hall voltage) across an electrical conductor, transverse to an electric current in the
conductor and an applied magnetic field perpendicular to the current, due to the magnetic field
deflecting the moving charge carriers (electrons and holes).
Write the equation for the De Broglie relationship and explain its components - correct answer
✔✔ p = h/λ. The De Broglie relationship relates the momentum (p) of a particle to its
wavelength (λ), with h being Planck's constant. It demonstrates wave-particle duality.
, Explain in words and mathematically the Heisenberg Uncertainty Principle - correct answer ✔✔
ΔxΔp ≥ ℏ/4π. The Heisenberg Uncertainty Principle states that the more precisely the position
(Δx) of a particle is determined, the less precisely its momentum (Δp) can be known, and vice
versa. It underscores the intrinsic limit in simultaneously measuring these two complementary
variables in quantum systems.
Explain why classical mechanics failed to explain electron behavior in certain environments -
correct answer ✔✔ e.g. the photoelectric effect,Classical mechanics failed to explain
phenomena like the photoelectric effect, where electrons are emitted from metals exposed to
light. Classical theories predicted a delay in emission and dependency on light intensity, which
was not observed in experiments, highlighting the need for quantum mechanics.
Explain how Planck, De Broglie, Einstein, Bohr, Schroedinger contributed to the field of quantum
mechanics - correct answer ✔✔ Planck introduced quantization of energy, De Broglie proposed
wave-particle duality, Einstein explained the photoelectric effect using photons, Bohr
introduced quantized electron orbits, and Schroedinger developed wave mechanics and the
time-independent Schroedinger Equation, collectively shaping quantum mechanics.
Explain the interpretation of an electron wave function for the time independent Schroedinger
Equation - correct answer ✔✔ The square of the wave function (|ψ|^2) from the time-
independent Schroedinger Equation gives the probability density of finding a particle in a
particular state at a given position and time. It provides insights into the spatial distribution and
energy of electrons in atoms and molecules.
Describe energy potential barriers/wells and the concept of electron tunneling through an
energy barrier - correct answer ✔✔ Energy potential barriers/wells are regions in space where
particles experience a potential energy change. Electron tunneling through a barrier refers to
the quantum phenomenon where electrons move through a potential barrier, despite having
less energy than the barrier, due to their wave-like nature and probabilistic existence across
space.
questions well answered
Explain the particle model for an electron - correct answer ✔✔ The particle model for an
electron considers it as a point particle with a definite mass, charge, and spin. It can be localized
in space and follows classical Newtonian mechanics under certain conditions.
Explain the wave model for an electron - correct answer ✔✔ The wave model for an electron
describes it as a wave that is spread out over space, having wave-like properties such as
interference and diffraction. The wavefunction describes the probability distribution of an
electron's position.
Define in words the concepts of mean free path, mean free time, drift mobility, and drift
velocity. - correct answer ✔✔ Mean free path is the average distance a particle travels between
collisions. Mean free time is the average time between collisions. Drift mobility is the average
drift velocity of carriers per unit electric field in a semiconductor. Drift velocity is the average
velocity of a particle when moving in one direction, averaged over a time interval.
Write the equation for the Lorentz Force and explain what it describes - correct answer ✔✔ F =
qE + qv x B. The Lorentz Force describes the force experienced by a charged particle in an
electromagnetic field, composed of electric (qE) and magnetic (qv x B) force components.
Explain in words the Hall Effect - correct answer ✔✔ The Hall Effect refers to the production of a
voltage (Hall voltage) across an electrical conductor, transverse to an electric current in the
conductor and an applied magnetic field perpendicular to the current, due to the magnetic field
deflecting the moving charge carriers (electrons and holes).
Write the equation for the De Broglie relationship and explain its components - correct answer
✔✔ p = h/λ. The De Broglie relationship relates the momentum (p) of a particle to its
wavelength (λ), with h being Planck's constant. It demonstrates wave-particle duality.
, Explain in words and mathematically the Heisenberg Uncertainty Principle - correct answer ✔✔
ΔxΔp ≥ ℏ/4π. The Heisenberg Uncertainty Principle states that the more precisely the position
(Δx) of a particle is determined, the less precisely its momentum (Δp) can be known, and vice
versa. It underscores the intrinsic limit in simultaneously measuring these two complementary
variables in quantum systems.
Explain why classical mechanics failed to explain electron behavior in certain environments -
correct answer ✔✔ e.g. the photoelectric effect,Classical mechanics failed to explain
phenomena like the photoelectric effect, where electrons are emitted from metals exposed to
light. Classical theories predicted a delay in emission and dependency on light intensity, which
was not observed in experiments, highlighting the need for quantum mechanics.
Explain how Planck, De Broglie, Einstein, Bohr, Schroedinger contributed to the field of quantum
mechanics - correct answer ✔✔ Planck introduced quantization of energy, De Broglie proposed
wave-particle duality, Einstein explained the photoelectric effect using photons, Bohr
introduced quantized electron orbits, and Schroedinger developed wave mechanics and the
time-independent Schroedinger Equation, collectively shaping quantum mechanics.
Explain the interpretation of an electron wave function for the time independent Schroedinger
Equation - correct answer ✔✔ The square of the wave function (|ψ|^2) from the time-
independent Schroedinger Equation gives the probability density of finding a particle in a
particular state at a given position and time. It provides insights into the spatial distribution and
energy of electrons in atoms and molecules.
Describe energy potential barriers/wells and the concept of electron tunneling through an
energy barrier - correct answer ✔✔ Energy potential barriers/wells are regions in space where
particles experience a potential energy change. Electron tunneling through a barrier refers to
the quantum phenomenon where electrons move through a potential barrier, despite having
less energy than the barrier, due to their wave-like nature and probabilistic existence across
space.
