Electrostatic Precipitator/Smoke Precipitator - How it Works/How to Make

This electrostatic precipitator, or smoke precipitator, gets rid of most smoke by using high voltage to collect smoke particles. This shows how the electrostatic precipitator works and how to make your own electrostatic precipitator.

Hewitt-Drew-it! PHYSICS 90. Electric Potential

Compared with electric potential energy, with novel situations.

 

Hewitt-Drew-it! PHYSICS 89. Electric Fields

Paul explains Electric Fields.

 

Hewitt-Drew-it! PHYSICS 88 Coulomb's Law

Compared to the law of gravity, with examples.

 

The Wimshurst Machine

A Wimshurst electrostatic generator, working on the principle of induction, generates high voltage differences and sparks between two movable electrodes.   By increasing the distance between the electrodes, higher potential differences can be built up.

Electrostatic induction refers to the principle that charges in an object (especially a conductor) redistribute themselves in the presence of nearby charges. Opposite charges are attracted to each other, while similar charges are repelled. Larger charges can be stored by connecting the knobs to Leyden jars which are component parts of the machine.

 

Breakdown of Air

Grounding rod tips of different sizes are used to discharge a large Van de Graaff generator. The larger the curvature of the tip, the more charge must build up to break down the air, resulting in longer sparks.

The electricity ionizes air molecules, releasing quick flashes of light. A pointed tip barely sparks at all, but instead creates an electric field so strong that it forms a tiny ball of plasma just beyond the tip. This is known as "St. Elmo's Fire", and is just visible when all the lights are turned off.

Fluorescent and Neon Tubes in an Electric Field

A fluorescent tube swings at the end of a long plexiglass rod. It is made to rotate and then brought near the Van de Graaff generator. The tube lights up when there is a potential difference between its ends. This happens when it is pointing radially away from the Van de Graaff. The same can be done with a small neon tube.

 

Science off the Sphere: 1.21 Legowatts

NASA Astronaut Don Pettit gets creative with an educational LEGO kit aboard the International Space Station. Answer the challenge question at www.physicscentral.com/sots for a chance for prizes!

Other Science off the Sphere videos

Surface Distribution of Charge

A tear drop shaped conductor on an insulating stand is charged. Charge is scooped up from various points on the surface of the conductor with a proof plane and transferred to an electroscope. It is demonstrated that the charge density is greater at the areas of greater curvature.

See other MIT physics demos

Science off the Sphere: Dancing Droplets

NASA Astronaut Don Pettit, aboard the International Space Station, demonstrates some interesting interplay between water droplets and charged knitting needles in microgravity.

Other Science off the Sphere videos

Charge and Electric Field of a Hollow Conductor

A conducting sphere is charged with a Wimshurst Machine. Charge is removed from the outside of the sphere and placed on an electroscope, which deflects outwards. When the procedure is done for the inside of the sphere, it is found that no charge resides there. Conducting balls are used to examine the effect of the sphere's electric field on the displacement of charge. The field induces opposite charges on the balls and, again, the effect is shown using the electroscope.

Other demonstrations from MIT