A vertical straight wire carries a current of 3 A downward
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Magnetism and Electromagnetism · Magnetism and Electromagnetism
Problem
A vertical straight wire carries a current of 3 A downward. Three points P, Q and R lie on a horizontal line through the wire at perpendicular distances 2 cm, 4 cm and 8 cm respectively from the wire.
(i) Taking the magnetic field strength at P as BP, express the field strengths BQ and BR in terms of BP.
(ii) Arrange the three points in order of decreasing magnetic field strength and justify your answer.
(iii) If the current in the wire is doubled while the positions of P, Q and R remain unchanged, by what factor does the magnetic field strength at Q change?