Static Electricity? Can someone tell me 3 benificial uses of static electricity?

Question

and please tell me how each works so I can have a better understanding. Thanks, I appreciate your help :o)

Answer 1

1) Xerox photo copiers use static electricty. A smooth selenium metal drum is uniformly negatively charged. Then an image is projected on the drum. The places where light falls lose their charge, but the dark areas remain charged. The drum rotates over a tray of toner, made of carbon black and powdered wax. The toner is positively charged and so is attracted to the negative areas of the drum. Then a piece of positively charged paper is brought close to the drum. This causes the toner (with the image) to be transferred from the drum to the paper. Lastly the paper is heated to melt the wax in the toner and fix the image to the paper.

2) There are certain types of dust/pollen filters called electrostatic precipitators. A fan draws dusty air through two sets of electrodes. The first set of electrodes are sharply pointed and negatively charged. This causes electrons to leave the electrodes and attach to dust particles. Since the dust particles are negatively charged they are attracted to the second set of electrodes, which are smooth wires and positively charged. Thus the dust is removed from the air.

3) There is a device that automatically sorts the highest quality coffee beans. Individual beans are made to fall, one at a time, through a reflective spectrographic analyser. This device very rapidly uses spectrography to analyse the bean's chemistry and determines if the bean is of the finest quality. Then the falling bean drops past a needle electrode which imparts a negative charge on it. Next the falling bean passes a smooth plate electrode. If the bean is a reject, a negative charge is applied to the plate. Because like charges repel, the falling bean is diverted into the "reject" bin. High quality beans are allowed to simply drop into the "good" bin. The coffee bean sorter processes about 30 individual beans per second.

Answer 2

Powder coating, and you can have painting for free. You ground the object and charge the paint, when you switch on the spray it attracts the charged paint.

Laser printers. You charge up a belt, burn off the charge with a laser, pick up the toner with the charge, then melt it onto the paper.

Air filters. You charge the grids and the crud in the air sticks to them. If you go too far you generate ozone and poison everyone.

Answer 3

I cant even tell u one.