A uniformly charged circular loop of radius a√2 is placed in the xy-plane with its centre at the origin. At what position on the positive z-axis is the electric field maximum?
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Question

A uniformly charged circular loop of radius a√2 is placed in the xy-plane with its centre at the origin. At what position on the positive z-axis is the electric field maximum?

G1 Physics · Accepted Answer

For a uniformly charged ring of radius R, the electric field on its axis is E(z) = kQz/(R²+z²)^(3/2). For maximum field, set dE/dz = 0: (R²+z²) - 3z² = 0 ⇒ R² - 2z² = 0 ⇒ z = R/√2. Here R = a√2. Therefore z = (a√2)/√2 = a. Correct option: D.