Application of Electrostatics

Electrostatic Paint Spraying

• Paint droplets from an aerosol become charged from rubbing against the nozzle of the spray
• Droplets attract to the metal body of the car which is earthed
• Since droplets have the same charge, they repel each other in the spray and spread out evenly, resulting in an even coat of paint

Photocopier

• Makes use of photoconductor which conducts when it is in light and is an insulator when it is dark
• Whole surface of drum is charged positively by rotating it near a highly charged metal wire
• Light gets reflected off the page and projected onto the drub
• White parts of the page causes the parts to become conducting and lose their charges
• Other parts correspond to the black parts ot the page
• Fine particles are attracted to the charged areas of drum and pressed against the copy paper
• Heat is supplied to fix the toner powder onto the paper surface

Electrostatic Precipitator

Used to remove fine ash and dust from chimneys

• Contains metal plates that are positively charged and a number of metal rods running through them which are negatively charged
• Air molecules around the rods are ionized. Positive ions attracted back to rods
• Negative ions picked up by tiny particles of ash and dust
• Negatively charged particulates are attracted to the metal plates where they are collected