Magnets
What is a permanent magnet?
A magnet whose magnetic domains/atoms remain aligned even after removing
What two things can generate a magnetic field?
A magnet and a current carrying wire
What device is used to measure electric current?
Galvanometer
Where is the magnetic field strongest on a magnet?
At the poles
What do the variables mean in the following equation?
(VOut)/(VIn) =(N2)/(N1)
Vout = Output voltage
Vin = Input voltage
N2 = turns in secondary coil
N1 = turns in primary coil
What is an electromagnet?
A temporary magnet created when there is an electric current inside a wire coil
Often wrapped around an iron core
What is electromagnetism?
The interaction between electric charges and magnets
What device is used to change electrical energy into mechanical energy?
Motor or alternator
What are the two magnetic poles? Which two poles attract? Which poles repel?
South and North poles
South and North poles attract
South and South poles repel
North and North poles repel
What do the variables mean in the following equation?
I = V/R
I = current
V = voltage
R = resistance
How can a permanent magnet be made?
By exposing the magnet to a stronger magnetic field
What is electromagnetic force?
The force of attraction or repulsion between electric charges and magnets
What device is used to change mechanical energy into electrical energy?
Generator
What is a magnetic field?
A region of space that surrounds a magnet and exerts a force on other magnets and objects made of magnetic materials
A transformer reduces the electrical current from 36,000 V to 120 V. If the secondary coil has 10 turns, how many turns does the primary coil have?
(VOut)/(VIn) =(N2)/(N1)
(120)/(36000) =(10)/(N1)
120N1 = 360000
360000/120 = N1
3000 = N1
What is a the coiled wire in an electromagnet called?
Solenoid
What is electromagnetic induction?
The generation of an electric current by a changing magnetic field
How does a transformer work? Explain in detail (1 min)
An alternating current is passed through the primary coil, which as the current changes direction, it changes the magnetic field. This changing magnetic field causes the electrons and atoms in the secondary coil to move to align with the magnetic field, inducing an alternating current in the secondary coil as the charged particles move
What is it called when groups of atoms all align their magnetic fields?
magnetic domains
A transformer has 2 turns in its primary coil and 50 turns in secondary coil. If the output voltage is 250 V, what is the input voltage?
(VOut)/(VIn) =(N2)/(N1)
(250)/(VIn) =(50)/(2)
500 = 50VIn
500/50 = VIn
10 = VIn
What are three ways the strength of an electromagnet can be changed?
By changing the voltage of the electric current
Coiling the wire more or less times
Using a magnet with more or less strength
Explain how electromagnetic induction works in detail (1 min)
Moving a magnet close to a wire coil or changing the electric current in a wire coil next to another wire coil changes the magnetic field of the first magnet. This changing magnetic field causes the atoms and electrons in the second wire coil to move to align to the changing magnetic field. This movement of charged particles causes electricity to flow in the second wire coil.
How does an electrical power plant generate electricity using a turbine? Explain in detail (1 min)
It burns fuel to heat up water into steam. As the steam rises, it turns a turbine connected to an electromagnet. As the turbine spins, it spins the electromagnet, which changes its magnetic field near a wire coil. The changing magnetic field induces a current in the wire coil, generating electricity
How are magnetic field lines drawn to show magnetic field strength and direction?
They are drawn closer together to show stronger magnetic forces and they are also always drawn from the North to the South poles
A wall outlet has a current of 60 Amps and a resistance of 2 Ohms. This current then passes through a transformer with a ratio of 20 to 1 in its primary coil to its secondary coil. What is the output voltage of the transformer?
I = V/R
60 = V/2
(60)(2) = V
120 = V
(VOut)/(VIn) =(N2)/(N1)
(VOut)/(120) =(1)/(20)
20VOut = 120
VOut = 120/20
VOut = 6