Electromagnets Flashcards
How does the national grid work?
High current and low voltage leads to high resistance. This means cables get very hot and lose energy whilst transporting electricity. To stop this, current is kept voltage is kept high and current is kept low in cables
National grid changes in current and voltage?
Power station-> high current, low voltage
Cables-> low current, high voltage
Consumer -> high current, low voltage
Step up?
Voltage increases
Power equation
Current(amps)X potential difference(volts)= power
What is power?
Energy transferred per second
Primary and secondary coil?
Must have the same amount of energy transferred as energy cannot be created or destroyed.
Step down?
Voltage decreases( less turns on secondary coil)
What is A.C?
Alternating current, current can flow in both directions in the wire
Motor effect?
When a current-carrying wife is in the presence of a megnaguc field and experiences a force
Force equation
Force = B X I X L
Newtons/amps/tesla X current X length of wire(metres)
Change in direction of current means?
Change in direction of magnetic field
Increase current results in?
Increase strength of magnetic field
What is an electromagnet?
A magnet that runs on electricity
Permanent magnet?
Always magnetic, attracts magnetic materials
What does it means if lines are closer together in a magnetic field?
Magnetic field is stronger
Earth’s magnetic field?
Made of electric currents in molten outer core- made of iron and nickel
How to change strength of electromagnet?
Change current change coils around the iron coil
Left hand rule?
Thumb = movement of force
First finger= magnetic field
Middle finger= current
Factors affect size of force?
Current
Strength of magnet
Angle between wire and field
Force depending on wire angle?
Force is highest when wire is perpendicular to magnetic field lines
Force is 0 when it’s parallel
Generator effect?
Moving a wire through a magnetic field produces current
Transformers equation
Vs X Is = Vp X Ip
Voltage in secondary coil X current in secondary coil is equal to voltage in primary coil X current in primary coil
Density equation
M/v
