Electric PotentialHardQuestion 31453
Question
Potential on axis of a uniformly charged disc (surface charge density σ, radius R) at distance x:
- Aσ/(2ε₀)(√(R²+x²)−x)Correct
- Bσx/(2ε₀)
- CkσR/x
- DσR/(ε₀x)
Correct answer
σ/(2ε₀)(√(R²+x²)−x)
Explanation
V = σ/(2ε₀)[√(R²+x²) − x]. For x >> R: V → kQ/x (point charge limit). At x=0 (centre): V = σR/(2ε₀).