# Homework Help: Particle physics Questions

1. Mar 15, 2015

### Dhooy7

1. The problem statement, all variables and given/known data
1. If a charged particle moves in a straight line through some region of space, can you say that the

magnetic field in that region is zero? Explain.

2. How can the motion of a charged particle be used to distinguish between an electric field and a

magnetic field?

3. If a cosmic ray proton approaches the Earth from outer space along a line toward the center of the

Earth that lies in the plane of the equator, in what direction will it be deflected by the Earth’s magnetic

field? What about an electron? A neutron?

2. Relevant equations

1. If a charged particle moves in a straight line though space, you can say that the magnetic field in the region is zero. This is because the cosine of 0 is 0, so the magnetic field is zero. The force is in the same direction as the velocity which creates an angle of 0 degrees. Thus, there is no force.

2. I don't understand this at all. My professor was saying something about affecting the particles e field in a straight line versus curving for the e- field.

3. I don't know where to start on this one to be honest.

3. The attempt at a solution

2. Mar 15, 2015

### RaulTheUCSCSlug

3. For number 3, the professor or your book should have told you something about the earths core, and knowing that it has a metallic core that creates an electric field of some sort the magnetic poles are created right? So use this information to guide your thinking. Think of the earth as a great big magnet of some sort, and think of how electrons react in a magnetic field.

2. For number 2, think about what are the main differences between the fields, and how they react to electrons and protons. Refer back to your book for this.

3. Mar 15, 2015

### Dhooy7

2. A charged particle can be used to distinguish between an electric field and a magnetic field because a charged particle that is moving (or not moving right away) in an electric field will be accelerated in the direction of the electric field (straight line). However, a charged particle that is moving in a magnetic field will move in a spiral and curve.

Is number 1 right?

3. It won't be deflected. An electron will go to the right or left?

4. Mar 15, 2015

### RaulTheUCSCSlug

I didn't really read over number 1, but cos(0)=1 so you are wrong with the knowledge you presented, show the equation you used next time.

Also for Number 2, assuming that you are in a conceptual physics class (Paul G. Hewett book maybe?) You should think about how a charged particle reacts in a magnetic field and how it reacts in an electric field and I am confused on what you mean by "spiral", do you mean that it will tend to want to go to one of the poles, if so, then you may be on the right track.