A long straight conductor carries a current I. Two points P and Q are located at perpendicular distances r and 2r from the conductor. What is the ratio of the magnetic field intensities at P and Q?
Correct: A
The magnetic field around a long straight conductor is given by B = μ₀I/(2πr). Since B ∝ 1/r, the ratio of magnetic field intensities at P (distance r) and Q (distance 2r) becomes B_P/B_Q = (μ₀I/(2πr)) / (μ₀I/(4πr)) = 2:1.