Gaokao Exam Gaokao Physics: Electromagnetism 6

Question 1

The electric field inside a conductor in electrostatic equilibrium is:

Accepted Answer

Zero

Answer

Free charges in a conductor redistribute until the internal field is zero; all excess charge resides on the surface.

Question 2

A negatively charged particle enters a magnetic field directed into the page moving to the right. The particle experiences a force directed:

Accepted Answer

Downward

Answer

F = qv × B; for negative charge moving right (v = +x̂) in field into the page (B = −ẑ): v × B = x̂ × (−ẑ) = +ŷ, then F = (−e)(+ŷ) = −ŷ, i.e. downward.

Question 3

Two identical resistors are first connected in series, then in parallel, to the same battery. The ratio of total power dissipated (parallel/series) is:

Accepted Answer

4

Answer

P = V²/R_eq. Series R_eq = 2R; parallel R_eq = R/2. P_par/P_ser = (R/2)⁻¹/(2R)⁻¹ = 2R/(R/2) = 4.

Question 4

The resonance frequency of an LC circuit with L = 4 mH and C = 100 pF is:

Accepted Answer

~252 kHz

Answer

f = 1/(2π√(LC)) = 1/(2π√(4×10⁻³ × 10⁻¹⁰)) ≈ 252 kHz.

Question 5

The electric flux through a closed surface surrounding a charge of +Q is (in SI units):

Accepted Answer

Q/ε₀

Answer

Gauss's law: Φ_E = Q_enc/ε₀.

Gaokao Exam Practice Test

Gaokao Exam Practice Test

Gaokao Exam Gaokao Physics: Electromagnetism 6