An electroscope is a device used to test if an object is charged. It consists of a metal ball, rod and leaves. When neutral, the leaves stay together, but when charged, they repel each other. Charging can occur through contact or induction. Induction involves charging an object without direct contact by using a nearby charged object to move its electrons. Grounding provides a path for charges to travel to or from the ground.

1. Charging and Discharging Objects

2. An electroscope is a device that allows you to test whether an object is charged The main parts of an electroscope are a metal ball , a metal rod and metal leaves Electroscopes metal ball metal rod metal leaves

3. The ball, rod and leaves are all conductors Conductors allow electrons to move easily through them Electroscopes metal ball metal rod metal leaves

4. Electroscopes When the electroscope is neutral , the leaves stay together + - + - + - + - + + - + - + - + - + - + - + - + - + - + - + - + - + - - + -

5. Electroscopes When the electroscope is positively or negatively charged , the leaves repel each other (separate) + - + - + - - - - - - - - - - - - - - + - + - + - + + + + + + + + - + -

6. When a neutral object is touched by a charged object, some of the charge transfers to the neutral object and the neutral object becomes charged . Charging By Contact - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

7. When a negatively charged object touches a neutral object, electrons move to the neutral object making it negative Charging By Contact - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ebonite rod

8. When a positively charged object touches a neutral object, electrons move from the neutral object to the positive object and make the neutral object positive Charging By Contact + + + + + + + + + + + + + + + + + + - + - + - + + + + - - + - + - + - + - + + + + + + + + - - - - acrylic rod

9. When an insulating material is charged by contact, the charge stays on the insulator at the point where it is touched Charging By Contact

10. When a conducting material is charged by contact, the charge spreads out over the whole surface of the conductor. Charging By Contact

11. Induction is the movement of electrons within a substance, caused by a nearby charged object, without direct contact Induction

12. If you rub a rubber balloon on your hair, electrons will transfer from your hair to the balloon, making the balloon negative Induction

13. When you bring the negatively charged balloon near a neutral wall, the electrons on the balloon repel the negative charges on the wall, making that part of the wall positive Induction

14. The balloon is said to induce a charge on the wall because it charges the wall without contacting it Induction

15. Grounding is the process of connecting a charged object to the Earth’s surface Grounding (Symbol for grounding)

16. When you connect a charged object to the ground, you provide a path for charges to travel to or from the ground Grounding

17. When you charge an object by induction , you use a charged object to induce a charge in a neutral object Then you ground the newly charged object so that it retains the charge Charging By Induction

18. Charging By Induction Step 1 : When a negatively charged object comes near a neutral electroscope, it repels the electrons in the neutral electroscope

19. Charging By Induction Step 2 : When you ground the neutral electroscope, you provide its electrons with a path away from the repulsive influence. Some electrons leave the electroscope.

20. Charging By Induction Step 3 : When you remove the ground and the charged object, the electroscope is left with a positive charge because it has lost some electrons

21. Charging By Induction Step 1 : When a positively charged object comes near a neutral electroscope, it attracts the electrons in the neutral electroscope

22. Charging By Induction Step 2 : When you ground the neutral electroscope, you provide a path for electrons to go toward the positive influence.

23. Step 3 : When you remove the ground and the charged object, the electroscope is left with a negative charge because it has gained some electrons Charging By Induction

24. Once an object is charged , the charges are trapped on it until they are given a path to escape When electric charges are transferred very quickly , the process is called an electrical discharge Electrical Discharge

25. Sparks are an example of electric discharge

26. Lightning is an example of a very large electrical discharge caused by induction Electrical Discharge

27. Lightning

28. Lightning Lightning can strike up to 15km from where it is raining If you can hear thunder , you are in striking distance Safe shelter includes large buildings or vehicles (provided the windows are rolled up and you do not touch metal parts of the vehicle)

29. Lightning Avoid the highest point of land (e.g. under a tree) because lightning tends to strike these areas Stay away from objects that conduct electricity (e.g. bicycles, golf clubs, lawn mowers etc.)