Electrostatics

Question 1

When a polythene rod is rubbed with a cloth, what happens?

Answer 1

Electrons are scraped from the duster to the rod
Rod becomes negatively charged

Question 2

When an acetate rod is rubbed with a cloth, what happens?

Answer 2

Electrons move from the rod to the duster
Rod becomes positively charged

Question 3

Describe how an inkjet printer works

Answer 3

Droplets of ink are forced out of a fine nozzle so becomes electrically charged
The droplets are deflected as they pass between two plates. A voltage is applied to the plates (one is positive one is negative)
Droplets are attracted to the plate of opposite charge and repelled from the plate with the same charge.
The size and direction of the voltage across each plate changes so each droplet is deflected to hit a different place on the paper.

Question 4

Describe how a photocopier works

Answer 4

Image plate is positively charged. An image of what you’re copying is projected onto it. Whiter bits of the image make light fall on the plate, so charge leaks away in those places. Charged parts attract negatively charged black powder which is transferred onto positively charged paper. The paper is heated so the powder sticks.