To demonstrate Electrostatic Shielding

Objective 

To demonstrate electrostatic shielding.  

 

Theory 

What is electrostatic shielding  

Electrostatic shielding is a method of shielding or protecting a particular region or space or any sensitive instrument from the effect of the external field produced by an electric charge. It is a phenomenon seen when a Faraday cage is used to block the effects of an electric field. The effects of external fields on the internal contents are blocked using the cage. 

History of electrostatic shielding  

According to the practical demonstration of electrostatic shielding, the fact of keeping this instrument inside the conductor is there is no electric charge inside a closed conductor when there is no charge inside it.   

Michael Faraday took a high-voltage generator, prepared a large, wired cage supported on insulators, and sat inside the cage with gold leaf electroscopes, which were electric field detectors. When this cage was charged with an induction machine, Faraday observed no deflection in electroscopes. Also, he could sit safely and comfortably inside the cage. 

  

Faraday Cage 

The Faraday cage is a container that shields conductive objects from external electric fields.  

Michael Faraday invented the Faraday cage in 1800. Whenever he charged the metal cage, which acts as an electrical conductor, he observed that the charges only appeared on the surface and had no effect on the interiors. He lined a chamber in metal foil on a bigger scale, allowing high-voltage discharges from an electrostatic generator. He used an electroscope, a device that detects electric charges, to confirm his theory that the metal foil outside the surface was conducting electricity. In contrast, the rest of the room was devoid of them. 

                              

                                                 

                                  Fig: The earthed can C shields the disc D from the field of ebonite rod 

 

Applications of electrostatic shielding  

During a lightning thunderstorm, it is advised to stay inside the car and not under trees or in the open ground because the outer metallic body of the car acts as an electromagnetic shield from the lightning. 

In a coaxial cable, the central conductor is protected by an electrostatic shield by connecting the outer conductor to the ground. 

 

Learning Outcomes

  • Students can understand the term electrostatic shielding. 
  • Students can understand the working principle of electrostatic shielding. 
  • Students can understand the application of electrostatic shielding.