A very long straight conductor carries a current I. A point P lies at a perpendicular distance d from the conductor. What is the magnitude of the magnetic field at point P?
Correct: A
The magnetic field around a long straight conductor is given by Ampere’s Law: B = μ₀I/(2πd). This is derived by considering a circular Amperian loop around the wire. Incorrect options often result from missing constants or misapplying the formula.