A charged particle moving in a magnetic field experiences a force equal to:

Thus, the magnitude of the force that the proton experiences is given by:

The magnetic field is perpendicular to the proton's velocity, therefore, we have
. Replacing the given values, we obtain:

Answer:
Explanation: please see attached file I attached the answer to your question.
A, C, and D are true when a light spot appears, so those are false.
The answer is therefore B.