Regents Physics 4

Question 1

An electron moves perpendicular to a magnetic field. The magnetic force on the electron acts:

Accepted Answer

Perpendicular to both its velocity and the field

Answer

The magnetic force on a charged particle is F = qv × B, which is always perpendicular to both the velocity and the magnetic field.

Question 2

Which phenomenon provides evidence that light behaves as a wave?

Accepted Answer

Diffraction

Answer

Diffraction—the bending of light around obstacles—is a wave behavior that demonstrates the wave nature of light.

Question 3

A 60 W light bulb operates on a 120 V circuit. What is the current through the bulb?

Accepted Answer

0.5 A

Answer

P = IV, so I = P/V = 60/120 = 0.5 A.

Question 4

Which of the following best explains why a compass needle points north?

Accepted Answer

The Earth acts as a giant magnet with a magnetic south pole near geographic north

Answer

Earth's geographic north pole is near its magnetic south pole; since opposite poles attract, the compass needle's north pole points toward it.

Question 5

An object in uniform circular motion experiences a centripetal acceleration directed:

Accepted Answer

Toward the center of the circle

Answer

Centripetal acceleration always points toward the center of the circular path.

Regents Practice Test