# Homework Help: Another Magnetic Force Problem

1. Sep 24, 2009

### balling12

1. The problem statement, all variables and given/known data
A singly charged positive ion has a mass of 2.51 X 10-26 kg. After being accelerated through a potential difference of 264 V, the ion enters a magnetic field of 0.570 T, in a direction perpendicular to the field. Calculate the radius of the path of the ion in the field

2. Relevant equations
r=mv/qB

3. The attempt at a solution
Im not sure how to get the value of v from the information in the problem.

2. Sep 24, 2009

### kuruman

What is the kinetic energy of a singly charged ion that is accelerated (from rest we assume) through a potential difference of 264 Volts?

3. Sep 27, 2009

### balling12

1/2mvf^2?

4. Sep 27, 2009

### Fightfish

That's definitely a true expression; but the question is, what is its value equal to?

5. Sep 27, 2009

### balling12

the potential energy?

6. Sep 27, 2009

### Fightfish

Strictly, no. It is equivalent to the change in potential energy of the system magnitude-wise. (recall conservation of energy)

7. Sep 27, 2009

### balling12

1/2mvf^2+1/2mvi^2= mghi+mghf

8. Sep 27, 2009

### Fightfish

Err..no gravitational potential energy is involved here; the particle is accelerated through a (electrical) potential difference. What is the change in electrical potential energy of the particle upon passing through the electric field?

9. Sep 27, 2009

### balling12

would it be Change In P.E.=(q)(potential difference)
(1.6X10^-19)(264)= 4.224X10^-17