- Involves placing charged rod close to the conductor (s) without contact
- This induces redistribution of charges in conductors
Important
If they are in contact → electrons move If they are brought close together → electrons are attracted/repelled
Charging 1 Conductor
Overview
| Step 1 | Step 2 | Step 3 | Step 4 |
|---|---|---|---|
| Place charged rod close to the conducting sphere. - Unlike charges accumulate → on side nearer to charged rod → while like charges accumulate on other side.  | Touching sphere on right → allows electrons to be repelled → further away into persons body | Remove hand from sphere | Remove charged rod |
| Single sphere method for inducing excess Positive charge |
| Step 1 | Step 2 | Step 3 | Step 4 | Result |
|---|---|---|---|---|
| 1. Neutral conducting sphere → placed on insulating stand 2. Negatively charged rod is brought near (but not touching) sphere. | 1. Negatively charged rod repels negative charges (electrons) to side of sphere furthest away from rod 2. Excess positive charges → remain on the side of the sphere neare While holding charged rod in place → touch the negatively charged side of sphere with finger. - finger → provides a path for electrons to flow out of the sphere → to earth (earthing) - Result → excess positive charges → are present in sphere. - Electrons flow to earth earth earth earth th th | While holding charged rod in place → remove your finger to stop the earthing process. Lastly remove charged rod. | Charges → redistribute themselves → throughout the entire sphere → once charged rod is removed. Sphere is now positively charged. |
Single sphere method for inducing excess Negative charge
| Step 1 | Step 2 | Step 3 | Step 4 | Result |
|---|---|---|---|---|
| 1. Neutral conducting sphere → placed on insulating stand 2. Positively charged rod is brought near (but not touching) sphere. | Positively charged rod → attracts negative charges (electrons) to side of sphere nearest to rod. Excess positive charges → remain on the side of the sphere furthest away from the rod. | While holding charged rod in place → touch positively charged side of sphere with finger Electrons flow to the sphere → fingers provide a path for electrons to flow from earth to sphere to neutralise positive charges (earthing) As a result → excess negative charges are present in sphere | While holding charged rod in place → remove finger → stop earthing process. Lastly remove charged rod | Charges redistribute themselves → throughout sphere → once charged rod is removed. Sphere is now negatively charged |
Charging 2 Conductors
| Step 1 | Step 2 | Step 3 |
|---|---|---|
| 2 neutral conducting spheres →brought in contact which each other. - Each sphere placed on insulating stand. Place positively charged rod close to (but not touching) one of the conducting spheres → that are in contact. Positively charged rod → causes negative charges (electrons) → on both spheres to be attracted towards it → as a result → excess negative charges accumulate on the surface of sphere P nearest to the rod. Excess positive charges → remain on the surface of sphere Q → furthest from the rod.  | Keeping rod in position → separate 2 spheres → to isolate → 2 groups of opposite charges | Remove the charged rod. → excess charges within each sphere will be redistributed. → 2 spheres now have equal but opposite charge. (amount of excess positive charges on sphere Q = number of excess negative charges on sphere P)  |
| Alternative → Using Negatively Charged Rod |
| Step 1 | Step 2 |
|---|---|
 |  |
| negatively charged rod may also be brought near sphere P Charged rod induces: positive charges on surface of sphere P nearest to rod negative charges on the surface of sphere Q furthest from rod | After 2 spheres are separated → negatively charged rod is removed. Excess charges within each sphere → will redistribute themselves. - Sphere P becomes positively charged - Sphere Q becomes negatively charged |
Sample
Explain what you understand by induction
- B is a neutral conducting body. When brought near A, its free electrons are attracted by the positive charge on A and move to the left of B, leaving positive nuclei on the right. This process of induced charges separating on B is called induction.
make sure to state whether the objects/rods → are touching or not touching
Key words:
- neutralise equal number of positive charges (usually due to earth wire)
Between 2 spheres:
- between positive and negative charges → there is electrostatic forces of attraction
- between either both positive/both negative charges → there is electrostatic forces of repulsion
- when electrostatic forces of attraction between unlike charges > electrostatic forces of repulsion between like charges → attraction occurs
- works vice versa as well
Important
even when the sphere is drawn to only have either all positive/all negative charges, it still means it has the other kind of charge but there is just an excess of one
if sphere is connected to negative terminal of battery, it becomes negatively charged
ensure to use the word induced charges*
Note: electrons cannot flow from one touching sphere to the other if one is non conductor and other is a conductor