# Homework Help: Magnetic field question

1. Sep 24, 2014

### camel-man

A 3.60 mC charge moving at 862 m/s travels at right angles to a magnetic field, and experiences a .00425 N magnetic force.

Find the strength of the magnetic field.

F = qvB (not sure if the right angle makes a difference in the equation.)

B= .00425 /(3.60x10^-6)(862) = 1.37 T

A 53.0 mC charge is now moving at 1300 m/s and 550 to the same magnetic field.

Find the magnetic force exerted on the second charge.

F = (53x10^-6C) (1300m/s)(550T) = 37.8 N

Does this look correct? Also, I am wondering what if the angle was not a right angle? how would that differ the equation I would use..

2. Sep 24, 2014

### Staff: Mentor

F = qvB is true for a right angle between motion and magnetic field only, otherwise you need the cross-product of velocity and magnetic field.

And 550 what? Is that an angle? 55°?
The problem statement said you should use the magnetic field from the first subquestion. And 550T is not a reasonable field strength.

3. Sep 24, 2014

### camel-man

Ahh yes I'm sorry I copy and pasted it over and didn't realize it put a zero. It is 55 degrees. yes.