Lesson.3: Uses of Static Electricity Objectives Be confident in explaining the following uses of static electricity i

1. Lesson.3: Uses of Static Electricity Objectives Be confident in explaining the following uses of static electricity in some scientific detail. Photocopiers Dust Precipitators Defibrillators Paint Sprayers

2. Photocopiers

3. What do they do?

4. How it works A Photocopier uses static charge to apply toner (black powder) to the paper • A high voltage charged wire transfers positive charge to the drum

5. 2. The Drum becomes charged evenly over its whole surface.

6. 3. Light removes charge from the parts which are not to be printed.

7. 4. Charge attracts toner particles.

8. 5. Toner is rolled onto the page

9. 6. Toner is melted onto the paper.

10. Summary

11. Precipator

12. Electrostatic Precipitators.

13. How does it work ? Smoke particles become charged and are attracted to plates and stick to them.

14. Completing the story… • The dirt particles clump together • What happens to the mass of clumps? • Get heavier • What force increases as mass increases? • Gravity ! • So what will happen eventually to the large clumps? • Fall to the bottom

15. Precipitator with 40cm wide plate spacing on a 320-megawatt coal-fired power boiler Furnace/boiler Cleaned flue gas Gas with particles in from burning coal in the furnace Precipitated particles collected here

16. Precipitators Write the missing words in the correct order • Plates in a precipitator are charged to a high pd or ________. • Dirt particles become charged and are attracted to the _________ charged plates. • The dirt sticks to these meaning the smoke coming out is now ________. • As the dirt clumps up it becomes _______ enough to fall down the chimney. heavy oppositely cleaner voltage

17. Precipitators : Answers • Plates in a precipitator are charged to a high pd or voltage • Dirt particles become charged and are attracted to the oppositely charged plates. • The dirt sticks to these meaning the smoke coming out is now cleaner • As the dirt clumps up it becomes heavy enough to fall down the chimney. heavy oppositely cleaner voltage

18. The defibrillator Saving your life!

19. What happens here?

20. What is Fibrillation ? Normal heart rhythm • In some heart conditions the electrical impulses which are necessary for the proper operation of the heart fall into disorder • The heart chambers flutter rather than pulse rhythmically. • Little or no blood will be pumped like this so the sufferer is in mortal danger. Trace showing ventricular fibrillation

21. Defibrillation In order to save the life of someone with a fibrillating heart a defibrillator can be used. Electrolyte gel is smeared on electrodes (known as paddles) which are placed on the patients body either Side of the heart. A large voltage is applied across these electrodes to drive a current through the patient’s heart. This current can restore normal heart rhythms. If a persons heart is showing no electrical impulses then defibrillation will not revive them.

22. Safety • It is important when using a defibrillator that no one touches the patient or any exposed contacts on the defibrillator • Or else they may become the next patient! • A big enough electric shock can cause defibrillation.

23. Defibrillation implant

24. Defibrillation “When a heart is in disorder electrical paddles can be connected and a charge given to restart it” Questions • Why must there be a good contact between the paddles and the patient ? • Why must the doctor be insulated from the paddles ?

25. Paint Spraying

28. Summary of Paintspraying The paint is charged as it comes out of the nozzle. The paint spreads out in a spray due to repulsion The car must be connected to the opposite voltage. The paint is attracted to the oppositely charged car. The paint is applied evenly all over

29. Static Electricity True or False !

30. A photocopier works because of electrostatics. TRUE

31. If an object loses electrons, it becomes negatively charged. FALSE

32. It is important to connect an aeroplane to its tanker before refuelling. TRUE

33. Paint from a paint sprayer spreads out because all the paint particles have the same charge. TRUE

34. Oil tankers are filled with hydrogen before cleaning to avoid explosions. FALSE

35. The operator of a defibrillator should be attached to the patient FALSE

36. To use a defibrillator it must not be a connected to the patient’s chest FALSE

37. The dust collected from dust precipitators clumps together TRUE

38. In the paint shop of a car factory, the car body is given the same charge as the paint to make it stick better. FALSE

39. Soot particles stick to the plates in a dust precipitator. TRUE

40. Complete Higher ‘Static Electricity’ and ‘Uses of Static Electricity’ on pages 134 - 136. Foundation ‘Static Electricity’ on pages 123 - 124.

45. Foundation MARK SCHEME

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49. Recognise and describe how static electricity can be useful: • restarting a heart when it has stopped (defibrillator); • photocopiers/laser printers (detailed structural knowledge not required); • removing dust from smoke in chimneys; • paint spraying. • Describe (Explain) how static electricity can be useful for restarting the heart when it has stopped (defibrillator): • paddles charged; • good electrical contact with patient’s chest; • charge passed through patient to make heart contract; • care taken not to shock operator.

50. Describe (Explain) how static electricity can be useful for electrostatic dust precipitators to remove smoke particles etc from chimneys: • metal plates/grids put into chimneys; • connected to a high PD; • dust particles attracted to plate/grid; • dust attracts together to form larger particles; • dust falls back down chimney when particles are heavy enough. • Describe (Explain) how static electricity can be useful for paint spraying: • spray gun charged; • paint particles charged; • repel giving fine spray; • object charged oppositely to paint; • attracts paint; • even coat, less waste, shadows painted