Problems with static electricity
2 marks · EasyIn a photocopier, explain why the toner powder sticks to some parts of the drum but not to others.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
Toner sticks to the parts of the drum that are still electrically charged after exposure to light; toner does not stick where the charge has been removed by light.
Common mistakes: Saying 'sticks to the dark parts' without mentioning charge.
Show mark scheme and worked solution
Marking points
B1 · 1 mark · Says toner sticks only to charged areas of drum.
B2 · 1 mark · States that exposure to light removes the charge from other parts.
Worked solution
Only the areas of the drum that remain charged can attract and hold the toner powder. Light removes the charge from the other areas, so the toner does not stick there.