The correct option is (c) 2 and 3 only.
Explanation
A lightning conductor is a safety device installed on tall buildings to protect them from the damaging effects of lightning. It operates on the principle of providing a low-resistance path for the heavy electric discharge from the clouds to flow harmlessly into the earth.
Statement-wise Analysis:
- Statement 1 is Incorrect: A lightning conductor must be made of a material that conducts electricity efficiently. Wood is an electrical insulator and cannot conduct the massive electric charge associated with lightning. Therefore, the device consists of a metallic rod (usually made of copper or iron), not a wooden one.
- Statement 2 is Correct: The installation of a lightning conductor involves placing a metallic rod along the outer wall of the building. One end of the rod, often pointed, is kept exposed in the air above the highest point of the building. The other end is buried deep in the ground, connected to a metal plate, to ensure effective earthing.
- Statement 3 is Correct: The primary function of the metallic rod is to provide a direct and easy route (low resistance path) for the transfer of electric charge from the lightning strike to the ground. This prevents the electric current from passing through the building's structure, thereby avoiding structural damage or fire.
Key Takeaway:
A lightning conductor is a metallic rod that protects buildings by conducting the high electric charge of a lightning strike directly to the ground via a low-resistance path.