Question

Suppose you are in a cave deep within the earth. Are you safe from thunder and lightning? Justify your answer.

Answer 1

Hint
This question can be answered by stating a certain property of conductors. Due to this property, the net charge present inside the conductor will be zero. Earth being a conductor of electricity, will have this property. Hence we can say whether it is safer to be in a cave within the earth based on this.

Complete step by step answer
The vanishing of the electric field inside a cavity in a conductor is called the electrostatic shielding. Due to electrostatic shielding, the field inside a uniformly charged spherical conductor will be zero. The charge will always be distributed on the outer surface of the conductor.
We know that our earth is a conductor of electricity. Let us consider the earth to be a spherical conductor. A cave deep within the earth will have a net charge of zero when the lightning strikes. The charge will be distributed on the surface of the earth. Hence due to the electrostatic shielding, it is safer to be in a cave deep within the earth during thunder and lightning.

Note
It is safer to be inside a car rather than taking shelter under a tree when there is lightning. The electric field inside the car will be zero even though there is a charge distribution over the car. Another practical application for electrostatic shielding is that we enclose instruments inside metal boxes to protect it from the external electric field. Such metal boxes are called Faraday cages. The charge will always reside on the outer surface of the conductor. Surface density may be different at different points.