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.
I count four true. I will be happy to critique your thinking.
I think
A,B,E,G
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.
Thanks, i got it right. F was accepted.
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
To determine which of the statements for magnetism are true, let's analyze each statement:
A) B does work on a charge only when the charge has a velocity component perpendicular to B.
To verify this statement, we need to recall the formula for magnetic force experienced by a charged particle moving in a magnetic field, given by the equation F = qvBsinθ. Here, q represents the charge of the particle, v is its velocity, B is the magnetic field, and θ is the angle between the velocity vector and the magnetic field vector.
Since sin(90°) = 1, the only time the magnetic force does work on the charge is when the velocity component is perpendicular (or at an angle of 90°) to the magnetic field. Therefore, statement A is true.
B) B acts only on charges at rest.
This statement is incorrect. The magnetic force can act on charges in motion as well. In fact, the force is experienced by moving charged particles when they interact with a magnetic field.
C) B does work on a charge only when the charge has a velocity component parallel to B.
This statement is incorrect. As mentioned earlier, the magnetic force does work on a charge only when there is a velocity component perpendicular to the magnetic field, not parallel to it.
D) The earth's B-lines are parallel to the earth's surface at all points.
To determine the accuracy of this statement, we should consider the geographic variation of the Earth's magnetic field. The Earth's magnetic field is not perfectly aligned with its surface, but rather tilted at an angle. Therefore, the statement is false.
E) Unlike magnetic poles attract.
This statement is true. According to the laws of magnetism, magnetic poles of opposite polarity (North and South) attract each other.
F) The magnitude of the Earth's B is about 1E-4 Tesla.
To verify this statement, we need to determine the value of the Earth's magnetic field. The Earth's magnetic field has a magnitude of approximately 25 to 65 microteslas (µT) or 0.25 to 0.65 Gauss, which is equivalent to 2.5 to 6.5 × 10^(-5) Tesla. Therefore, the statement is true.
G) For a bar magnet, the B-lines exit through the N pole and return through the S pole.
This statement is true. For a bar magnet, the magnetic field lines (B-lines) emerge from the North (N) pole and re-enter through the South (S) pole, forming a closed loop.
In summary, the true statements are A, E, F, and G.