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A uniformly charged disc of radius R having surface charge density σ is placed in the xy plane with its center at the origin. Find the electric field intensity along the z-axis at a distance Z from origin:-

1. E = σ/(2ε0) (1 - Z/(Z² + R²)^(1/2))
2. E = σ/(2ε0) (1 + Z/(Z² + R²)^(1/2))
3. E = 2ε0/σ (1/(Z² + R²)^(1/2) + Z)
4. E = σ/(2ε0) (1 - Z/(Z² + R²) + 1/Z)

Correct answer: E = σ/(2ε0) (1 - Z/(Z² + R²)^(1/2))

Solution

The correct option accurately describes the electric field intensity along the z-axis due to a uniformly charged disc by incorporating the effects of both the surface charge density and the geometric relationship between the distance from the disc and its radius, leading to the correct expression for the electric field.

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