15. A charged particle enters a uniform magnetic field and follows the circular path shown in the drawing. (a) Is the particle positively or negatively charged? Why? (b) The particle’s speed is 140 m/s, the magnitude of the magnetic field is 0.48 T, and the radius of the path is 960 m. Determine the mass of the particle, given that its charge has a magnitude of

8.2 x 10-4 C.

 

w1112

 

We can see the magnetic force points to the left in this picture because of the curve of the path.  We know  is pointing out of the paper and  is pointing to the top of the page. 

The magnetic force is

 

Using the right hand rule,  points to the right.  Since the force is to the left, the charge must be negative to reverse this direction.

 

To find the mass use the sum of the forces in the radial direction.

 

Solve for m

 

Charge is negative !

 

 

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This page last updated on June 21, 2018