Applications of Static Electricity

Coal-burning power stations produce huge amounts of smoke pollution. This __________ is a cloud of small dust particles and/or ash. It can be removed by using static electricity.

Some thin wires are stretched across the centre of the chimney: These wires are charged __________ to about 50,000V and they cause the gas around them to become __________ or ionised.

Because of this, the smoke particles become positively charged. The smoke is then __________ by the wires, and attracted towards the earthed metal plates, where the dust sticks.

A mechanical hammer hits the plates every few minutes and the ash falls down into a bin. Later, it is used to make house-bricks (Cinder-blocks).

Bicycles and cars are painted using an electrostatic paint spray. The nozzle is given a charge and this makes a better spray - the droplets all have the same charge and __________ each other so that the paint spreads out to form a large cloud.

Less paint is needed because the charged droplets are all __________ to the object (even the back of it) because it has an opposite charge.

The object is then baked in an oven and the powder/droplets combine form a finished layer.

N.B. The same idea is used to make crop-spraying more efficient for farmers.

Negatively charged ink droplets are squirted between two oppositely charged metal plates across which a variable __________ is applied enabling the charges to be varied and swapped very quickly.

The charged droplets of ink are attracted towards the plate with the __________ charge. This allows them to be deflected to their precise vertical location on the page, while the carriage of the printer moves horizontally across the paper, to give a full range of ink projection.

N.B. This is now old technology but the principle is still important. Also, the system would work just as well with positively charged ink droplets.

Putting the following in the correct order:

• __________ The charge leaks away where the light falls on the drum
  
• __________ Light reflects off the original onto the drum
• __________ The image on the paper melts under the heater to give a permanent copy
• __________ 'Toner' powder sticks to the charged surface of the drum. The powder is transferred to the paper.
• __________ The drum gains charge