Electrostatic Shielding

During thunderstorm it is advised not stand in open or near tree.

Thunderstorm kills more people each year than tornadoes.

During lighting, even trees cannot protect itself from it. Tree cannot able to sustain this heavy current flow.

Therefore it is not safe for anyone to stand in open or near the tree during thunderstorm.

It is also observed that when light strike the car, it does not cause any harm to the person sitting inside car.

The outer surface of car act as some kind of shield to protect that man from the heavy charge flow.

Such shielding that block the influence of electric field is called electrostatic shielding.

Electrostatic shielding protect the hollow cavity from the outer electric field.

Assume a hollow sphere having a positive charge on it's outer surface.

Due to the charge on the surface, the Electric field is perpendicularly outward.

Let’s take a Gaussian surface inside the cavity as shown .

Inside this Gaussian surface charge is zero(q=0), because it just a empty space.

Hence, electric field inside the sphere is zero, and the surface of the sphere act as a shield.

Hence , This is called electrostatic shielding.

This shielding application is applied in electronic devices, where an electric component is protected from nearby electric field .

Electrostatic shielding also used in MRI to avoid interference with unwanted radio frequency.

Revision

During thunderstorm, light striking cause no harm to the person sitting inside the car.

Because all the charge will remain on the surface of car, The electric field inside the car become zero.

As there is no matter inside car cavity. i.e. It has only free space.

The surface around a cavity acts as a shield and protect the cavity from outside electrical influence.

This is called electrostatic shielding.

We have shielding application in electronic devices, MRI machines, etc.

The End