Electrostatic charging by friction is a process in which surface electrons are transferred from one electrical insulator to another electrical insulator when the insulators are rubbed together.
Category: Static Electricity
Define electric field.
An electric field is a region in which charged particles experience an electric force.
Describe the use of electrostatic charging in an electrostatic precipitator.
An electrostatic precipitator (ESP) is a device that removes particulate matter from exhaust gases using electrostatic forces. It is commonly used in industries such as power plants, cement factories and steel mills to control air pollution.
The basic principle of an ESP is to use an electric field to charge the solid particles in the gas stream, and then collect them on a charged surface.
1. The gas stream is first passed through a series of electrodes, which are typically made of metal wires or plates. These electrodes are charged with a high voltage, usually in the range of tens of thousands of volts.
2. As the gas stream passes through the electrodes, the solid particles in the gas become charged, either positively or negatively depending on the polarity of the electrodes. The charged particles are then attracted to an oppositely charged collection electrode, which is usually a flat metal plate or a series of plates.
3. As the particles collect on the collection electrode, they form a layer of solid deposits that can be removed periodically. This is done by rapping on the collection plates, which causes the solid deposits to fall into a hopper or other collection device.
Man Running Across Carpet
Charged Polystyrene Balls
(amendments needed. To be updated soon.)
Movement of electrons in discharge ball
An electrostatic generator is used to produce sparks as shown below.
The belt carries negative charges to the dome, making it negatively charged. Before a spark is produced, the discharge ball becomes positively charged.
Describe and explain the movement of electrons in the discharge ball and in the conducting rod as the ball becomes charged.
The electrons in the discharge ball and in the conducting rod moves downwards through the conducting wire, and to the ground.
Electrostatic charging by induction occurs in the ball and rod as they are placed near to the negatively charged dome. Like charges repel, causing the negatively charged electrons in the ball and rod to move away from the dome, escaping through the conducting wire to the ground.
Define electrostatic charging by induction.
It is a process in which electrical charges are redistributed in a neutral body by bringing an electrically charged object near to it.
Note: This type of induction is most effective in electrical conductors, but can also happen in some electrical insulators.
Better still, test it out yourself! 🙂
Can a charged insulator transfer its charges to a neutral conductor when they touch?
The short answer is no.
The insulator can be charged via electrostatic charging by friction, but not by electrostatic charging by induction. The charges do not travel easily from the insulator to the conductor or vice versa, simply by putting them in contact.
The electrons in the insulator are not delocalised, hence they are not able to move freely within its own body or cross over to another body to induce a charge.
Examples:
Answer is A
Answer is D
How is lightning formed?
In a storm cloud, water droplets are brought upwards in an updraft within the storm clouds. The droplets cool and freeze into hail and smaller ice particles as they rise upwards. The heavier hail particles that formed then fall back downwards, rubbing against the rising small ice particles.
Electrostatic charging by friction occurs, with the hail particles gaining electrons from the small ice particles. The heavier hail particles, which have become negatively charged, gathered at the bottom part of the storm clouds, while the lighter small ice particles, which have become positively charged, gathered at the top part of the storm clouds.
Electrons near the ground are repelled by the negatively charged bottom of the storm clouds, moving deeper into the ground, resulting in the objects on the surface of the ground becoming positively charged. As the negative charges build up at the bottom of the clouds, surrounding air particles are ionised, sending stepped leaders towards the ground. At the same time, the positively charged objects on the ground also ionise the air particles around them, sending streamers upwards towards the clouds.
When a particular stepped leader and streamer meet, a path is established, and the huge potential difference between the cloud and the object results in a massive current flow.
This huge current flow produces an enormous amount of heat, up to 30 000 deg C, which appear to us as the brilliant white-blue flash of a lightning flash.