A laser printer forms a charged pattern on a rotating drum before toner is added. The printer also contains metal rollers that contact moving insulating strips during testing.
The laser produces separate charged and uncharged areas on the drum.
Explain why these areas do not rapidly become evenly charged before the toner is applied.
In one test, the moving strip continually removes electrons from a metal roller. The roller is connected to earth before the strip starts moving.
Describe how this connection stops a large charge building up on the roller while the strip is moving.
In another test, a different moving strip continually transfers electrons onto a second metal roller. An earthed metal brush remains in contact with this roller as it turns.
Describe what happens to the transferred electrons while the roller is turning.
During a separate test, an unearthed metal roller is rubbed by a synthetic cleaning pad and becomes positively charged.
A student says:
'Positive particles must have moved from the cleaning pad onto the roller.'
Explain why the student is wrong.
80 exam-style questions on Edexcel GCSE Physics 11.2 Uses, dangers and electric fields, covering 11.2.1 Uses of electrostatic charge, 11.2.2 Dangers of sparking, 11.2.3 Electric fields, and 11.2.4 Electric fields and static electricity. Each one has a worked solution and a mark scheme showing where the marks go.