Question

What is electrostatic shielding? Mention one application of it.

Answer 1

Hint: To answer this question, recall Gauge law in electrostatics. The word “shielding” means protecting from something. Recall the faraday cage instrument and it’s working.

Complete answer:
We know from Gauge’s law, the electric field inside the charged hollow conductor is zero since the distribution of the charge on the conductor is such that it nullifies the net charge inside the conductor. If we place a sensitive electric instrument inside such a cavity, it will be free from any external electric disturbances.

The word “shielding” means blocking the external electric disturbances inside a metal cavity. Faraday cage is the instrument used by Michael Faraday that consists of metal bars joined such that it forms a cage. If we expose this cage to an artificial lightning bolt, the person standing inside the cage remains unharmed even if the lightning occurs close to him. The effect we called it electrostatic shielding.

We have seen that if we are stuck in a thunderstorm accompanied with lightning, we are advised not to come out of the car or bus because the outer metal surface of the car behaves as electrostatic shielding from the lightning. We know that the lightning is nothing but transfer of charges to the ground where it occurs. Even when the charge transfers to our car, it gets spread over the outer surface of the car. We know from Gauge’s law, the electric field inside the hollow charged conductor is always zero irrespective of the magnitude of the electric field outside the conductor.

We have seen the application of electrostatic shielding that protects the person inside the car stuck in the thunderstorm accompanied by the lightning. We can give other applications of the electrostatic shielding that TV cable uses the same phenomenon.

Note:To answer this question, students must understand Gauge’s law in electrostatics. It states that total electric flux in a closed cavity or loop is proportional to net electric charge enclosed by the loop. In our case, the net charge inside the cage is zero. Therefore the electric flux inside the cage is also zero.