NDA2026General AbilityGeneral ScienceActual
A lightning rod with sharp tip reduces damage risk. Which one of the following is the primary reason for it?
Options
- AIt attracts lightning directly.
- BThe sharp tip reduces the local electric field.
- CIt enhances field and promotes continuous corona discharge.
- DIt repels charged clouds.
Correct answer
C. It enhances field and promotes continuous corona discharge.
Step-by-step solution
A lightning rod has a sharp tip, which means the radius of curvature at the tip is very small. Since surface charge density is inversely proportional to the radius of curvature, the charge density at the sharp tip becomes very high. The electric field near the surface of a conductor is given by E = ₀ . Thus, the intense charge density creates a very strong local electric field. This strong electric field ionizes the surrounding air molecules, leading to a continuous corona discharge. This discharge helps in partial