Applications of Static Electricity & Electrostatic Devices

Introduction:

Objects get charged by rubbing or by conduction; when they are brought close to each other, we see that:

• The objects with the same electric charge repel each other.
• The objects with opposite charges attract each other.

Fig-: 1 Nature of electrostatic force

Explanation:

Applications of Static Electricity

1. Laser Printer:

The major parts of a laser printer are:

• Image drum
• Powdered ink or toner
• Laser unit
• Paper tray

 Fig-: 2 Laser Printer

The outside of the drum is made positively charged by being lasered with the shapes of what is to be printed, so because the text is positively charged, the negatively charged ink is attracted to the text as opposite charges attract.

Fig-: 3 Working of a laser printer

The next stage is for the image drum to roll over the paper for printing to take place. The paper is more positively charged than the outside of the image drum. As the image drum rotates over the paper, the negatively charged powdered ink is attracted to the positively charged areas on the drum as it rolls over the paper, sticking to the paper as the paper is more positively charged than the drum, so the negatively charged ink is attracted to the positively charged paper.

2. Electrostatic Paint Spraying:

The spray nozzle is connected to the negative terminal of an electrostatic generator. As the paint droplets (negatively charged) leave, they repel each other and spread out to form a fine cloud of paint. The metal item (here a car) to be painted is connected to the positive terminal. The positively charged metal body attracts the negatively charged paint.

Fig-: 4 Electrostatic paint sprayer

Advantages of Using an Electrostatic Paint Sprayer:

• In this process of spray painting, the paint gets sprayed evenly over the surface of the body to be painted.
• It takes very little time to paint.
• A very small amount of paint is consumed in comparison with the normal way of painting.

Fig-:5 Advantages of electrostatic paint Sprayer

3. Filters and Chimneys

Filters and chimneys are important because houses release a lot of pollutants through their chimneys when wood and coal are burned, and this is bad for the environment. A solution is to use filters that remove pollutants.

Fig-:6 Filter or Chimney

4. Electrostatic Crop Sprayer:

Electrostatic sprayers for crops are useful because when someone is pouring insecticides onto their crops, a lot is wasted. The wastage of these insecticides is a problem for farmers as they waste money, and in case you didn’t know, insecticides are chemicals that kill insects. A solution to this problem is to use electrostatic sprayers.

Fig-: 7 Crop sprayer

Fig-: 8 Electrostatic crop sprayer

This diagram represents the nozzle of an electrostatic sprayer. These black arrow lines represent the droplets of insecticides that have been made to have the same charge by the nozzle, and because they have the same charge, these droplets repel each other. As they leave the nozzle. This allows the droplets to spread evenly around the plant, and underneath the plant, the droplets are attracted to the crops by induction. The advantages of using an electrostatic sprayer for crops are that they spread out evenly and less is wasted.

The Advantages of Using an Electrostatic Sprayer for Crops are:

• The insecticides are spread out evenly.
• A very small quantity of insecticides is wasted.
• The wastage of these insecticides is a problem for farmers as they cost a lot. This can be reduced by using an electrostatic crop sprayer.

Summary

• Most of the devices based on electrostatics are based on the principle that unlike charges attract each other and like charges repel each other.
• The devices which work on electrostatics are:
• Laser printer
• Electrostatic paint sprayer
• Electrostatic crop sprayer
• Electrostatic chimney or filter