Presentation on theme: "Electrostatics and Charge LO: explain electrostatics in terms of transfer of electrons and build up of static charge Dusters that attract dust. Crackles."— Presentation transcript:
Electrostatics and Charge LO: explain electrostatics in terms of transfer of electrons and build up of static charge Dusters that attract dust. Crackles when combing hair. Cling film sticking to your hands. Dust being attracted to television screens. Clothes clinging to each other in a dryer. Getting a shock after rubbing your feet on a carpet and then touching a metal object. A lightning strike. TASK: Discuss with your partner, What links all of these events?
Static Charge Challenge Number of seconds you rub the balloon Number of pieces of paper attracted 0 10 20 30 40 50 Write a conclusion to this experiment As you rub the balloon on your jumper you build up more ______ ______ and _____ pieces of paper are _______ to the balloon
Friction can be used to create a static charge. How can static charge be created? If an insulator is rubbed with a cloth, it can become charged in one of two ways: The insulator ends up with an overall negative charge. Electrons move from the cloth to the insulator. The insulator ends up with an overall positive charge. Electrons move from the insulator to the cloth. OR
Attracting and repelling Rod in the stirrupRod in your handAttract or repel? Polythene (black)acetate (clear)attract acetate repel acetatepolytheneattract polythene repel 1 a Do the two polythene rods have the same charge as each other, or different charges? b Explain your answer to part a. 2 Do the two acetate rods have the same charge as each other, or different charges? 3 a Do you think the acetate rod and the polythene rod have the same charge as each other? b Explain your answer to part a. Conclusion 4 Copy and complete these sentences. If two objects have the same type of charge, they … If two objects have opposite charges, they … Copy the table into your book, do the experiment then answer the questions
What are the forces between charges? The forces between charges can be investigated using rods made of insulating materials. What happens when two positively-charged acetate rods are placed near each other? The rods repel each other because they have the same overall charge. What will happen if one rod is replaced with a charged polythene rod? rods repel each other acetate rods The rods attract each other as they have opposite charge
Can you think of anywhere the build-up of static electricity may cause a problem http://www.youtube.com/watch?v=gct 1BmKNvU0
Van de Graff generators A charge builds up on the dome due to electrons being “______ off” by the belt. If a big enough ______ is built up then the voltage becomes high enough to _____ the air molecules and the electrons “___” down to Earth – this is an electric _________. ONLY electrons move! Words – charge, jump, current, rubbed, ionise
Dangers of static During refuelling the fuel gains electrons from the pipe, making the pipe positive and the fuel negative. The resulting voltage may cause a spark – bad news! Solution: Either earth the fuel tank with a copper rod or connect the tanker to the plane by a copper conductor.