A point charge of +q moves with constant speed v along the +x-axis
PHYSICS · Multi-part · CBSE · Physics · Moving Charges and Magnetism · Moving Charges and Magnetism
Problem
A point charge of +q moves with constant speed v along the +x-axis. At the instant the charge passes the origin, three observation points are located as follows:
• Point A: on the +y-axis at coordinates (0, d, 0)
• Point B: on the –y-axis at coordinates (0, –d, 0)
• Point C: on the +z-axis at coordinates (0, 0, d)
The region is otherwise free of magnetic and electric fields.
(1) Describe the direction of the magnetic field produced by the moving charge at Point A. Express the direction in words relative to the coordinate axes.
(2) Explain how the direction of the magnetic field at Point B compares with that at Point A and justify your answer.
(3) Would an observer located at Point C detect a magnetic field at the instant described? Explain fully, referring to the spatial relationship between the velocity vector and the position vector from the charge to Point C.
(4) Suppose the moving charge were –q (same magnitude of charge, opposite sign) while all other conditions remain unchanged. Describe and justify the new magnetic-field directions at Points A and B.