3.7.5.2 - Moving Charges in a Magnetic Field

Question 1

What is the force on a stationary particle in a magnetic field?

Answer 1

No force.

Question 2

What is the force on a moving charge always?

Answer 2

Perpendicular to its direction of travel.

Question 3

What is the motion of a charged particle in a magnetic field?

Answer 3

Circular motion. It will follow a circular path.

Question 4

If you rearrange F = mv^2 / r with F = BQv, what does r equal?

Answer 4

r = mv / BQ

Question 5

What happens as the radius of the path increases?

Answer 5

The mass or velocity increase.

Question 6

What happens as the radius of the path decreases?

Answer 6

B or Q increase.

Question 7

Describe a cyclotron and what it does?

Answer 7

Charged particles are fired into one of the electrodes. The magnetic field makes them follow a semi circular path and then leave the electrode.

Question 8

What happens and why does it happen in a cyclotron when a charged particle leaves the first electrode?

Answer 8

An applied potential difference between the electrodes accelerates the particles across the gap, entering the next electrode. The increased velocity causes them to follow a larger circular path.

Question 9

What does f = apart from 1/T and v/d?

Answer 9

BQ / 2 pi m