What is the rule of charges?
Like charges repel, opposites attract
In electric fields, what is the direction of the force dependent on?
Positive charge
In electric fields, what is the strength of the force reliant on?
Density of field lines
What happens when you apply friction to an object?
Objects become charged positively due to loss of electrons
Objects are charged negatively by gain of electrons
Eg. Cloth on rod= rod as positive, cloth as negative
What happens when static discharge occurs?
- Electrons seek a path to earth
- Charge body is moved closed to conducting material
- Electrons jump from negatively charged body to the conductor
- This happens very quickly and cause a spark
- Depending on the amount of charge, these spots can be tiny or huge
How do you determine the size of sparks form static discharge?
The amount of charge
How do you reduce the risk of accident as a result of static discharge?
By earthing
How is static discharge dangerous?
Can be dangerously near flammable materials and cause fires
Uses of static discharge: (4)
- Heart defibrillators
- Photocopier/laser printers
- Filtering factory smoke
- Spray painting cars
Why can’t insulators not conduct electricity?
Electrons can’t flow throughout the material and are fixed
Why can conductors conduct electricity?
Their electrons can flow as they are delocalised
What happens when 2 insulators are rubbed together?
Electrons are transferred from one objects to another (one comes positive and one becomes negative) so they are charged by friction
What happens when 2 condo toes are rubbed together?
Electrons will flow in and out of them cancelling any effect so they stay neutral
When does a positive static form?
When objects loses electrons
When does a negative static form?
When an object gains electrons
When does sparking occur?
