# A magnetic field of 0.0200 T [up] is created in a region....

• LionLieOn
In summary, an electron moving at 5.00 X 10^6 m/s [N] in a magnetic field of 0.0200 T [up] will experience a force of 1.6 x 10^-14 N [WEST]. There is no change in the direction of the magnetic field, as it is assumed to be externally generated and held constant. The question is asking for the initial force direction, so there is no time for the field to change. Some classmates may have lost marks for incorrectly assuming that the electron would change the direction of the magnetic field, but this is not the case. It is important to use proper terminology and not confuse geographic directions with magnetic polarities.
LionLieOn

## Homework Statement

A magnetic field of 0.0200 T [up] is created in a region

Find the initial magnetic force on an electron initially moving at 5.00 X 10^6 m/s [N] in the field.

## Homework Equations

Work clarification and I would like to ask a question in relation to the direction of FM.

## The Attempt at a Solution

FM=(1.6*10^(-19) C)(5.00*10^6 m/s)(0.0200 T)
FM=1.6 x 10^-14 N

Since it is an ELECTRON, it would alter the direction of velocity, changing it from NORTH to SOUTH . With that said, Magnetic field is [UP], Velocity is [SOUTH] and FM is [WEST]. Therefore my final answer is FM=1.6 x 10^-14 N [WEST].[Is my answer right?]I'm unsure of my answer (Above.) as I was told from 2 of my classmates that I did it wrong. They said that an ELECTRON changes both Velocity's and Magnetic field's direction. However, I looked at the examples my teacher did and he only changed Velocity's direction.So I was just wondering who's approach is right, my friends or mine?

You did fine. The magnetic field is assumed to be externally generated and held constant. Besides, the question is looking for the initial force direction, which means at the first instant the electron encounters the field. So there would be no time for the field to change (which it doesn't, anyways).

I wonder how your friends handled their changing magnetic field direction?

Does anyone else see a problem with using North East and Up coordinates for a magnetic field problem? N and S mean something specific in a magnetic field. I mean I'm sure this is worked correctly due to the statement that the field is "up". However normally if you tell me a particle is moving north in a magnetic field I'm going to think it is traveling along the field lines toward the north magnetic pole. I think this is unnecessarily confusing.

Cutter Ketch said:
Does anyone else see a problem with using North East and Up coordinates for a magnetic field problem? N and S mean something specific in a magnetic field. I mean I'm sure this is worked correctly due to the statement that the field is "up". However normally if you tell me a particle is moving north in a magnetic field I'm going to think it is traveling along the field lines toward the north magnetic pole. I think this is unnecessarily confusing.
So, it's a great case of, "Don't confuse the map for the territory"

Magnet polarities were first defined by noting which end of a bar magnet (compass needle) was attracted to and hence pointed towards the geographic north. Of course, that mean that the pole that sits near the geographic pole is really a magnetic south pole...

gneill said:
You did fine. The magnetic field is assumed to be externally generated and held constant. Besides, the question is looking for the initial force direction, which means at the first instant the electron encounters the field. So there would be no time for the field to change (which it doesn't, anyways).

I wonder how your friends handled their changing magnetic field direction?

Oddly enough, my classmates lost marks for changing the magnetic field. When my teacher asked how they changed the Magnetic field, they simply said "Because of the electron." and my teacher went on to explain how that is not the case. In short, he basically said what you said.

Thank you so much for reviewing my work and for clarifying the change in direction. I would of thanked you earlier but I was in class. Again thank you!

You're welcome. Glad I could help.

## 1. What is a magnetic field?

A magnetic field is a region in space where magnetic forces are present, created by moving electric charges.

## 2. How is a magnetic field created?

A magnetic field can be created by electric currents, permanent magnets, or changing electric fields.

## 3. What does "0.0200 T [up]" mean in relation to the magnetic field?

0.0200 T [up] refers to the strength and direction of the magnetic field. In this case, the magnetic field has a strength of 0.0200 Tesla and is directed upwards.

## 4. What is the unit of measurement for a magnetic field?

The unit of measurement for magnetic field is the Tesla (T) in the SI system.

## 5. What is the significance of creating a magnetic field?

Magnetic fields have many practical applications, such as in motors and generators, medical imaging, and data storage. They also play a crucial role in understanding the behavior of charged particles in space.

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