Practise explaining electrostatic charging, attraction and repulsion, practical variables, and safety or use cases involving conductors and insulators.
A student uses this apparatus to investigate static electricity.
The positively charged ball is suspended vertically on a long length of string.
The ball is made of a material that is a good electrical conductor.
Name a material that is a good electrical conductor.
Explain, in terms of the movement of charged particles, how the ball has become positively charged.
The student places a centimetre scale behind the length of string.
The string lines up with the 5.0 cm mark on the scale when the ball is in its resting position, as shown in diagram 2.
The student brings a negatively charged polythene rod near to the right side of the ball.
The ball moves, as shown in diagram 3.
Explain how the movement of the ball shows that the charge on the polythene rod is negative.
In diagram 3, the string lines up with the 7.2 cm mark on the scale.
The student moves the polythene rod slightly further away from the ball.
Predict a possible reading on the scale.
reading = ............ cm
The student extends the investigation by measuring the reading on the scale for rods made from different materials.
As a control variable, the student charges each rod by rubbing it with a cloth the same number of times.
Give two other control variables for the student's investigation.
1 ............
2 ............
The bar chart shows the results of the student's investigation.
Deduce what can be concluded about the charge on each of the rods used in the investigation.
Use information from the bar chart to help your answer.
A student uses this apparatus to demonstrate the effect of electric charge.
He pours some fine powder into a funnel.
The fine powder moves through a length of plastic tubing and falls into a metal can.
The metal can rests on a metal cap.
The metal cap is connected to a thin piece of metal via a metal rod.
When the powder lands in the can, the thin piece of metal moves away from the metal rod.
Explain why the thin piece of metal moves away from the metal rod.
A coulombmeter measures electric charge.
The student connects a coulombmeter to the metal can.
When all the powder has landed in the can, the coulombmeter shows a reading of .
Which statement is true for the metal can?
it gains negatively charged electrons
it loses negatively charged electrons
it gains positively charged electrons
it loses positively charged electrons
The student suggests that this demonstration is similar to refuelling an aircraft.
The powder represents the fuel and the metal can represents the fuel tank in the aircraft.
Explain how the student should modify this apparatus to demonstrate how to minimise the dangers when refuelling an aircraft.
You may add to the diagram to help your answer.