Question

Explain electrostatic shielding and its applications.

Answer 1

Hint: To solve this question, recall Gauge law in electrostatics. The word “shielding” means protecting from something. We need to recall the topic of faraday cage instruments which protect a person from electric lightning and how they work.

Complete answer:
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. We call it electrostatic shielding.Electrostatic shielding is a method of shielding or protecting a particular region or space or any sensitive building/instrument from the effect of the external field produced by an electric charge.

Now, let’s look at the electrostatic shielding applications:
Electrostatic Shielding in Cars: It is safe to sit inside the car during a lightning thunderstorm because the metallic body of the car works as an electrostatic shield. The concept of electrostatic shielding is used in wires carrying audio signals. to protect them from external interference viz: electric field produced because of the atmospheric electricity or electric sparks.

Electrocution: To protect themselves from being killed by an electric shock or electrocution, linemen wear suits that are made of Faraday cages.Elevators in buildings act as an electrostatic shield as the cell phone, radio, and audio signals get shielded. The coaxial cables in the outer conductor are connected to the earth to provide electrostatic shielding to the signals that are transferred by the central conductor.

Note: Students should also know the concept of phenomena of magnetic shielding which suggest that the magnetic field inside the cavity is zero. This will help us to design sensitive and costly watches and place them inside the cavity, so that there is no effect of external magnetic field.