Gaokao Exam Gaokao Physics: Electromagnetism 7

Question 1

A charged particle with charge q and mass m is accelerated from rest through a potential difference V, then enters a magnetic field B perpendicular to the field. The radius of its circular motion is:

Accepted Answer

√(2mV/q)/B

Answer

From ½mv² = qV: v = √(2qV/m); then r = mv/(qB) = m√(2qV/m)/(qB) = √(2mV/q)/B.

Question 2

Kirchhoff's current law (KCL) is based on the principle of:

Accepted Answer

Conservation of charge

Answer

KCL states that the algebraic sum of currents at any junction is zero, reflecting charge conservation.

Question 3

The SI unit of inductance is the Henry (H). 1 H is equivalent to:

Accepted Answer

All of the above are equivalent

Answer

1 H = 1 V·s/A (from EMF = L dI/dt) = 1 T·m²/A (from flux linkage) = 1 Ω·s; all three expressions are dimensionally equivalent.

Question 4

An electric dipole consists of charges +q and −q separated by distance d. The electric field at the midpoint between the charges is directed:

Accepted Answer

From +q toward −q

Answer

Both charges produce fields at the midpoint; the +q field points away from +q (toward −q) and the −q field also points toward −q; they add in the same direction.

Question 5

A generator converts mechanical energy to electrical energy. The process is governed by:

Accepted Answer

Faraday's law of electromagnetic induction

Answer

Generators work by rotating coils in magnetic fields, inducing EMF according to Faraday's law.

Gaokao Exam Practice Test

Gaokao Exam Practice Test

Gaokao Exam Gaokao Physics: Electromagnetism 7