NSAA NSAA Physics - Electricity and Magnetism 3

Question 1

What is the energy stored in a capacitor of capacitance 4 F charged to 3 V?

Accepted Answer

18 J

Answer

Energy = ½CV² = ½ × 4 × 9 = 18 J.

Question 2

In a step-up transformer, the primary coil has 100 turns and the secondary has 500 turns. If the primary voltage is 20 V, what is the secondary voltage?

Accepted Answer

100 V

Answer

Vs/Vp = Ns/Np → Vs = 20 × (500/100) = 100 V.

Question 3

A positive charge is released from rest between two parallel plates with the positive plate on the left. In which direction will it accelerate?

Accepted Answer

To the right (toward negative plate)

Answer

Electric field points from positive to negative plate; positive charges accelerate in the field direction, toward the negative plate.

Question 4

Two point charges of +2 C and +8 C are 3 m apart. The electric force between them is F. If the distance is halved to 1.5 m, the new force is:

Accepted Answer

4F

Answer

Coulomb's Law: F ∝ 1/r²; halving distance multiplies force by 4.

Question 5

An electron moves with velocity v perpendicular to a magnetic field B. What is the shape of its path?

Accepted Answer

Circle

Answer

The magnetic force always acts perpendicular to velocity, providing constant centripetal force, resulting in circular motion.

NSAA - Natural Sciences Admissions Assessment Practice Test

NSAA - Natural Sciences Admissions Assessment Practice Test

NSAA NSAA Physics - Electricity and Magnetism 3