மின்னலில் இருந்து தப்பிப்பது எப்படி?

Electrostatic shielding is a technique that protects an enclosed region from external electric fields by enclosing it within a hollow electrical conductor. Inside such a conductive enclosure, the electric field becomes zero, preventing outside electrical discharges such as lightning from harming anyone or anything inside.

Electric fields and forces

• Every electric charge is surrounded by an area of force known as an electric field.
• Scientists represent the direction and strength of this invisible force using imaginary lines called electric field lines.
• Oppositely charged objects attract each other, while objects with identical charges repel each other through electrostatic force.

Testing charges with an electroscope

An electroscope is an instrument used to detect the presence of electric charge. It consists of a glass bottle containing a central copper wire connected to two light aluminium leaves at the bottom. When a charged glass rod touches the exposed wire, like charges transfer down to both leaves, causing them to repel each other and spread apart.

How electrostatic shielding works

• In an experiment with a Van de Graaff generator, artificial lightning discharges toward an aluminium cylinder.
• Free charges inside the aluminium cylinder rearrange themselves in response to the external electric field.
• Negative charges gather on the side facing the positive generator, while positive charges are repelled to the opposite side.
• The electric field lines travel only across the outer surface of the cylinder, leaving no electric field inside.
• A glass rod held inside the cylinder receives no induced charge, which is proven when the electroscope leaves fail to move.

Real-world protection

• Michael Faraday demonstrated this effect by constructing a wire enclosure known as a Faraday cage.
• When lightning strikes an airplane, electric currents pass harmlessly around the outer metal skin without entering the passenger cabin.
• Technicians working on high-voltage power lines wear special conductive suits that shield their bodies from dangerous electrical currents.