Question

Which of the following statements for magnetism are true? (Give ALL correct answers)

A) B does work on a charge only when the charge has a velocity component perpendicular to B.
B) B acts only on charges at rest.
C) B does work on a charge only when the charge has a velocity component parallel to B.
D) The earth's B-lines are parallel to the earth's surface at all points.
E) Unlike magnetic poles attract.
F) The magnitude of earth's B is about 1E-4 Tesla.
G) For a bar magnet, the B-lines exit through the N pole and return through the S pole.

Answer 1

I count four true. I will be happy to critique your thinking.

Answer 2

I think
A,B,E,G

Answer 3

How does magnetic fields act on a particle at rest?

E is "true", of one can agree what a magnetic pole exists. Isolated poles do not exist.

G. Yep, the definition for direction of magetic force lines is the direction of a mythical N pole would take.

The number of significant digits in F is one. That means that single digit is estimated. How close is 10 Gauss is 5 Gauss is the issue in one significant digit. I would argue F is true, but I can see an instructor arguing otherwise. What is not stated where is that B measured. I hate to assume at The surface of Earth, since it did not say that. So, all the advice I can give you on F is to go with the force, else, flip a coin. The statement is not so hot for a t/f statement.

Answer 4

Thanks, i got it right. F was accepted.

Answer 5

i have the exact same question, which ones were the correct ones, i have entered E,F,G and it still says its wrong. let me know, thanks