Electrostatic Potential And Capacitance

- Wondering why to study this chapter? Know the real world use of it!
Faraday's Cage:

One important result from the behaviour of conductors in an external field is:
any cavity in a conductor remains shielded from outside electric influence. This means the field inside the cavity is always zero. This is known as electrostatic shielding. The effect can be made use of in protecting sensitive instruments from outside electrical influence. The hollow conductor used is referred to as Faraday's Cage.
This is the reason why all the lines of sensitive devices, like telephone lines, have a metallic shield. The electric field from the High Voltage lines doesn't interfere with the signals transmitting inside this metallic shield.
Let's see how electric shielding finds applications in our daily life.
Electrostatic Shielding
3 mins
Capacitors in camera flash:

The light energy emitted by a flash is supplied by the capacitor. The batteries of small electronic devices having flash lights can't supply enough potential difference to power the high-voltage flash light. This problem is solved by employing a capacitor's capacity to store energy.
Capacitor in an Implantable Cardioverter Defibrillator:

Defibrillators are devices that restore a normal heartbeat by sending an electric pulse or shock to the heart. Some high-risk patients need an Implantable Cardioverter Defibrillator(ICD). An ICD consists of a capacitor, which stores the electrical charge needed to jolt the heart back into a normal rhythm.
Imagine there were no capacitors. Then the patient would need to carry a very large battery all time to generate the electric shock needed for their malfunctioning heart!
Principle of Van de Graff Generator:

Van de Graff Generator is a device used to build up extremely high potential difference in the order of a few million volts. It uses the unique property of conductors: that any charge imparted to the conductor accumulates only on its outer surface. The generator keeps building large amount of charge at the outer spherical conductor, till the breakdown field of air (3 x 106 V/m) is reached.  Due to their ability to generate high potential difference, Van de Graff Generators find use in sterilising food and process materials. The large potential difference kills all the harmful micro-organisms in the food.

Let's visualise its working through this video.
Vande Graff Generator
3 mins