9j electricity (physics) Flashcards
What is inside an atom?
- a central nucleus
- electrons orbiting the nucleus
- protons and neutrons in the nucleus
What happens when there is the same amount of electrons as protons in an atom?
It has no charge – it’s neutral.
What is the charge of an electron, proton and neutron.
- an electron has a negative charge
- a proton has a positive charge
- a neutron has 0 charge (it’s neutral)
What happens when you rub two materials together?
Electrons will be transferred from one material to the other, giving it a charge of static electricity. The material that loses electrons has a positive charge.
Why can’t protons or neutrons be transferred from one material to another?
Because they are fixed inside the nucleus.
What will happen with two opposite charges?
They will attract each other.
What will happen with two of the same charges?
They will repel each other.
Define an electric field.
The space around a charged object where it will attract or repel other charged objects.
Define resistance.
How easy or difficult it is for an electric field to flow through it.
If there is a higher voltage, what will happen to the current?
There will be a higher current (if the resistance stays the same)
If there is a higher resistance, what will happen to the current?
There will be a lower current (if the voltage stays the same)
Name 3 things the resistance of a wire depends on.
- the material it’s made from
- its length (longer wire = higher resistance)
- its thickness (thicker wire = lower resistance)
Unit of measure for resistance.
ohms Ω
Unit of measure for current.
amps A
Unit of measure for voltage.
volts V
Formula for resistance.
resistance = voltage / current
A bar magnet is a…
permanent magnet
A wire with electricity flowing through it has a…
magnetic field around it
Electromagnet definition.
a coil of wire with an electric current flowing through it (it is only magnetic while the current is flowing)
Name 3 ways an electromagnet can become stronger.
- increasing the number of coils on the wire
- increasing the size of the current (by increasing the size of the voltage)
- using an iron core
Define the motor effect.
if a wire carrying a current crosses a magnetic field, the wire will experience a force
What does a motor consist of?
a coil of wire in a magnetic field
What happens when there is a current in the coil?
There is a force on each side of the coil that makes it turn
Name 3 ways a motor’s speed (or the force it provides) increases.
- increase the size of the current
- increasing the strength of the magnetic field
- increasing the number of turns of wire on the coil
