Static electricity and electric fieldsIB MYP Physics: Mind map

Exam questions on Static electricity and electric fields

1. A student in a school laboratory rubs a dry polythene rod with a woollen cloth. Afterwards the rod is able to pick up small scraps of paper. Careful tests show that the rod has become negatively charged and the cloth has become positively charged.
   Explain why the polythene rod becomes negatively charged when it is rubbed with the cloth.2 marks
2. At an airport, a fuel tanker pumps aviation fuel into an aircraft through a long rubber hose. As the fuel rushes through the hose, friction makes charge build up on the hose and the tanker. Before pumping begins, a thick metal cable is clipped from the tanker to the aircraft, and a second cable connects the aircraft to the ground.
   Explain why a spark between the tanker and the aircraft would be dangerous if the cables were not used.2 marks
3. A group of students investigate how the number of times a polythene rod is rubbed with a woollen cloth affects the amount of charge the rod gains. After rubbing, they touch the rod to the metal cap of a gold-leaf electroscope and use a protractor to measure how far the gold leaf rises away from the metal stem. The electroscope is discharged by touching the cap before every trial.
   Identify the independent variable, the dependent variable and one control variable in this investigation.3 marks