1. 1
   In a physics classroom demonstration, a polythene rod is rubbed with a dry duster. Both the rod and the duster are electrical insulators. After rubbing, the rod is found to attract small pieces of paper and repel another negatively charged rod held nearby.

   (a)

   Which type of charge builds up on the polythene rod after it has been rubbed with the duster?

   [1 mark]

   • ANegative, because the rod gains electrons from the duster
   • BPositive, because the rod gains electrons from the duster
   • CNegative, because the rod loses protons to the duster
   • DPositive, because the rod loses electrons to the duster

   (b)

   What charge does the duster have after the rod has been rubbed, and why?

   [1 mark]

   • ANegative, because it has lost electrons to the rod
   • BPositive, because it has lost electrons to the rod
   • CPositive, because it has gained electrons from the rod
   • DNo charge, because insulators cannot hold static charge

   (c)

   Explain, in terms of the movement of electrons, why the rod repels the other negatively charged rod but attracts the small pieces of paper.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An aircraft is being refuelled from a tanker using a long pipe. As the fuel flows quickly through the pipe, friction between the fuel and the pipe walls can cause static charge to build up on the aircraft and the fuel itself. If this charge is allowed to build up, a spark could ignite the fuel vapour.

   (a)

   Why is there a risk of a spark when fuel flows through the pipe during refuelling?

   [1 mark]

   • AFriction between the fuel and the pipe walls causes a static charge to build up on the aircraft
   • BThe fuel becomes magnetised as it flows through the metal pipe
   • CThe moving fuel increases the pipe's electrical resistance to zero
   • DThe fuel reacts chemically with the metal pipe to release electrons

   (b)

   Which safety measure is used to reduce the risk of a spark forming during refuelling?

   [1 mark]

   • AUsing a plastic pipe instead of a metal one to insulate the fuel
   • BIncreasing the speed at which fuel flows through the pipe
   • CConnecting the aircraft and the fuel tanker together with an earthing (bonding) cable before fuelling begins
   • DRubbing the pipe with a duster before fuelling begins

   (c)

   Explain why an earthing (bonding) cable between the aircraft and the tanker reduces the danger of static electricity during refuelling.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A photocopier reproduces a printed page by shining light from the original document onto a rotating drum. The drum's surface can hold an electrostatic charge, and fine toner particles are used to reproduce the pattern of dark and light areas from the original document onto paper.

   (a)

   Explain, in terms of electrons, how the drum of the photocopier becomes electrostatically charged, and how toner particles are then attracted to the charged areas of the drum.

   [3 marks]

   (b)

   Explain why an insulating material, rather than a conducting material, must be used for the toner particles and drum surface of the photocopier.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A museum exhibit from the 18th century displays an early electrostatic generator, used by scientists of the time to produce sparks and demonstrate the attraction and repulsion of charged objects. Visitors are shown a demonstration in which two different insulating materials are rubbed together to produce a visible spark.

   (a)

   Explain, in terms of the transfer of electrons, how rubbing two different insulating materials together produces electrostatic charge, and describe how the resulting charges lead to the forces of attraction and repulsion observed by early scientists.

   [6 marks]

   (b)

   Explain the dangers of static electricity in modern industrial settings such as fuel handling, and the benefits of static electricity in modern devices such as photocopiers and inkjet printers, referring to the movement and control of electrons in each case.

   [6 marks]

   Total for question 4: 12 marks

End of questions