Gaokao Exam Gaokao Physics: Electromagnetism 2

Question 1

Two charges +Q and −Q are separated by distance d. The electric potential at the midpoint between them is:

Accepted Answer

Zero

Answer

Potential is a scalar; V = kQ/(d/2) + k(−Q)/(d/2) = 0.

Question 2

A charged particle of mass m and charge q enters a region of crossed electric and magnetic fields (E perpendicular to B). For the particle to travel undeflected, its speed must be:

Accepted Answer

E/B

Answer

For equilibrium: qE = qvB, so v = E/B regardless of mass or charge.

Question 3

A transformer has 500 primary turns and 50 secondary turns. If the primary voltage is 220 V, the secondary voltage is:

Accepted Answer

22 V

Answer

V₂/V₁ = N₂/N₁ → V₂ = 220 × (50/500) = 22 V.

Question 4

Faraday's law states that the magnitude of the induced EMF in a loop is equal to:

Accepted Answer

The rate of change of magnetic flux through the loop

Answer

Faraday's law: |EMF| = |dΦ/dt|, where Φ is the total magnetic flux.

Question 5

An electron (e = 1.6×10⁻¹⁹ C) is accelerated through a potential difference of 500 V. Its kinetic energy gained is:

Accepted Answer

8×10⁻¹⁷ J

Answer

KE = qV = 1.6×10⁻¹⁹ × 500 = 8×10⁻¹⁷ J.

Gaokao Exam Practice Test

Gaokao Exam Practice Test

Gaokao Exam Gaokao Physics: Electromagnetism 2