Physics 250 Exam 2 Newest 2026 Questions
and Correct Detailed Answers Already
Graded A+
What is the common mistake regarding electric fields of sheets?-CORRECT
ANSWER-Confusing the field of a single infinite sheet with the field between two
oppositely charged sheets.
What is the formula for permittivity?-CORRECT ANSWER-ε = κε0, where κ is the
dielectric constant.
How does the electric field change when a linear dielectric fills a region?-CORRECT
ANSWER-E = E0 / κ.
What is the capacitance of a parallel-plate capacitor filled with dielectric?-
CORRECT ANSWER-C = κC0.
What does counterion screening refer to?-CORRECT ANSWER-Counterions
accumulate near a charged object and screen its electric potential.
What is the equation for the electric potential in the linearized Debye-Huckel
regime?-CORRECT ANSWER-ϕ(x) = ϕ0e^(-x/λD).
,What is the formula for Debye screening length?-CORRECT ANSWER-λD = √(εkBT /
Σ(ni * zi^2 * e^2)).
What factors affect the Debye screening length?-CORRECT ANSWER-Larger
temperature (T) increases λD; larger ion concentration (ni) decreases λD; larger
valence (|z|) decreases λD; larger permittivity (ε) increases λD.
What is the work done by the electric force in electrostatics?-CORRECT ANSWER-
Welectric = -∆U.
How is potential difference defined?-CORRECT ANSWER-∆V = Vf - Vi = -∫(E · dℓ).
What are the first steps to prepare for the Physics 250 Exam?-CORRECT ANSWER-
Read boxed formulas, 'must know' bullets, and common mistake boxes.
What is the formula for the electric field from a point charge?-CORRECT ANSWER-
E(r) = ke * q / r^2, where ke is Coulomb's constant.
What is the significance of electric field lines?-CORRECT ANSWER-They indicate
the direction a positive test charge would accelerate.
, What is the relationship between electric field and potential?-CORRECT ANSWER-
Electric field (E) is a vector; potential (V) is a scalar.
What happens to the electric field inside a conductor in electrostatic
equilibrium?-CORRECT ANSWER-The electric field (E) is zero inside the conductor.
What is the formula for capacitance?-CORRECT ANSWER-C = Q / ΔV, where Q is
charge and ΔV is potential difference.
What is the electric field just outside a conductor?-CORRECT ANSWER-E⊥,outside
= σ / ε, where σ is surface charge density.
What is the dipole moment of an electric dipole?-CORRECT ANSWER-p = q * d,
where q is charge and d is the separation vector.
What is the formula for torque on a dipole in a uniform electric field?-CORRECT
ANSWER-τ = p × E, where p is the dipole moment and E is the electric field.
What is the potential energy of a dipole in a uniform electric field?-CORRECT
ANSWER-U = -p · E = -pE cos θ, where θ is the angle between p and E.
and Correct Detailed Answers Already
Graded A+
What is the common mistake regarding electric fields of sheets?-CORRECT
ANSWER-Confusing the field of a single infinite sheet with the field between two
oppositely charged sheets.
What is the formula for permittivity?-CORRECT ANSWER-ε = κε0, where κ is the
dielectric constant.
How does the electric field change when a linear dielectric fills a region?-CORRECT
ANSWER-E = E0 / κ.
What is the capacitance of a parallel-plate capacitor filled with dielectric?-
CORRECT ANSWER-C = κC0.
What does counterion screening refer to?-CORRECT ANSWER-Counterions
accumulate near a charged object and screen its electric potential.
What is the equation for the electric potential in the linearized Debye-Huckel
regime?-CORRECT ANSWER-ϕ(x) = ϕ0e^(-x/λD).
,What is the formula for Debye screening length?-CORRECT ANSWER-λD = √(εkBT /
Σ(ni * zi^2 * e^2)).
What factors affect the Debye screening length?-CORRECT ANSWER-Larger
temperature (T) increases λD; larger ion concentration (ni) decreases λD; larger
valence (|z|) decreases λD; larger permittivity (ε) increases λD.
What is the work done by the electric force in electrostatics?-CORRECT ANSWER-
Welectric = -∆U.
How is potential difference defined?-CORRECT ANSWER-∆V = Vf - Vi = -∫(E · dℓ).
What are the first steps to prepare for the Physics 250 Exam?-CORRECT ANSWER-
Read boxed formulas, 'must know' bullets, and common mistake boxes.
What is the formula for the electric field from a point charge?-CORRECT ANSWER-
E(r) = ke * q / r^2, where ke is Coulomb's constant.
What is the significance of electric field lines?-CORRECT ANSWER-They indicate
the direction a positive test charge would accelerate.
, What is the relationship between electric field and potential?-CORRECT ANSWER-
Electric field (E) is a vector; potential (V) is a scalar.
What happens to the electric field inside a conductor in electrostatic
equilibrium?-CORRECT ANSWER-The electric field (E) is zero inside the conductor.
What is the formula for capacitance?-CORRECT ANSWER-C = Q / ΔV, where Q is
charge and ΔV is potential difference.
What is the electric field just outside a conductor?-CORRECT ANSWER-E⊥,outside
= σ / ε, where σ is surface charge density.
What is the dipole moment of an electric dipole?-CORRECT ANSWER-p = q * d,
where q is charge and d is the separation vector.
What is the formula for torque on a dipole in a uniform electric field?-CORRECT
ANSWER-τ = p × E, where p is the dipole moment and E is the electric field.
What is the potential energy of a dipole in a uniform electric field?-CORRECT
ANSWER-U = -p · E = -pE cos θ, where θ is the angle between p and E.
