Question

Are you relatively safe from lightning inside an automobile? Give two reasons.

Short answer

Yes, we are relatively safe from lightning inside an automobile because: (i) The metal body of the automobile acts as a Faraday’s cage, keeping the electric field inside the automobile zero. (ii) The charge spreads on the outer surface of the automobile and finds the path to the Earth through the tires.

Step-by-step solution

Faraday’s cage

Faraday’s cage is a protective enclosure that blocks the electric field inside it. It works on the principle of redistribution of excess charge on the outer surface of the metal cavity creating a zero electric field inside the cage.

Safe inside an automobile during lightning

We are relatively safe from lightning inside the automobile for the following reasons:

1. If a flash of lightning strikes the metal surface of an automobile, the charges brought by lightning spread on the outer metal surface of the automobile. Hence no charge resides in the interior of a conductor and the automobile acts as a Faraday’s cage, protecting the person inside it.
2. The charge on the metal surface cause a large potential difference between the vehicle and the Earth. The rubber tires burst due to high potential and the charges find their way to Earth.

Thus, we are comparatively safer inside a car.