Predict what will happen to the disk of an uncharged electroscope when a positiv
ID: 3307935 • Letter: P
Question
Predict what will happen to the disk of an uncharged electroscope when a positively charged obsject is brought near the disk.
I said: All of the positive charges in the disk will move towards the vanes in the electroscope, being repelled by the similarly charged obsject. When a positively charged object is brought near the uncharged disk of an electroscope then the positive charges attract the negative charges from the disk and repel positive charges from the disk. So, the unchaged disk will become positively charged.
QUESTION: Continue your previous answer so that you describe what happens to the charge in the other parts of the electroscope. Use this to infer what happens to the vanes.
Explanation / Answer
As soon as a positively charged object is brought near the Disc of uncharged Electroscope, following things happen
1. Polarisation of charge in the Disc and vanes, leading to seperation of positive and negative charges
2. Negative charges being mobile , will get attaracted towards towards positively charged object, and therefore will accumulate on the Disc, therefore Disc becomes negatively charged.
3. Due to flow of negative charges, ?Vanes are left with excess of positively charged, therefore Vanes will become positively charged.