Question

A charge travels through a uniform magnetic field and makes a counterclockwise circular path, as shown in the figure below. What is the sign of the charge? A It must be negative (B) It must be positive C It must be neutral D It may be positive or neutral E It may be negative or neutral

Please show work. The correct answer is A

Answer 1

• When considering the motion of a charged particle in a magnetic field, the relevant vectors are the magnetic field B, the velocity of the particle v, and the magnetic force exerted on the particle F. These vectors are all perpendicular to each other.
• The right hand rule states that, to find the direction of the magnetic force on a positive moving charge, the thumb of the right hand point in the direction of v, the fingers in the direction of B, and the force (F) is directed perpendicular to the right hand palm.
• since force is showinn downwards, it is possible when the particle is negatively charged