Review Direction of magnetic field lines Field around

• We already know current produces magnetic fields. • Michael Faraday wanted to

• The process of generating current this way is electromagnetic induction. • https:

How does this work? • In order to produce current, you need electrical energy.

EMF • Depends on – Magnitude of B-field – Length of wire in B-field

Generators • https: //www. youtube. com/watch? v=rn. PEtw Qtm. GQ

Generators • Invented by Faraday • Converts mechanical energy to electrical energy • Wire

• Connecting the generator to a circuit and the induced EMF will produce

Lenz’s Law • Induced current flows in a direction to oppose the change that

• If a generator produces a small current, then the opposing force will

Transformers • Device used to increase or decrease AC voltage • Change voltages without

• Has 2 cells that are insulated from each other, but wound around

Exit Slip • In your own words, describe how a generator works using a

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Review… • • Direction of magnetic field lines? Field around a current carrying wire F = BIL F = Bqv

Electromagnetic Induction

• We already know current produces magnetic fields. • Michael Faraday wanted to know if magnetic fields could induce current. • He placed a wire loop, which was part of a closed circuit, into a magnetic field. • When the wires moves up, the current is in one direction. • When the wires moves down, the current is in the opposite direction. • When the wire is held stationary or is moved parallel to the magnetic field lines, there is no current.

• The process of generating current this way is electromagnetic induction. • https: //www. youtube. com/watch? v=txm. Kr 69 j. GBk

How does this work? • In order to produce current, you need electrical energy. • Electromotive Force- (EMF) voltage – NOT A FORCE! • When the wire moves through the B-field, you exert force on the electrons and they move in the direction of the force. • Work is done on the electrons. • They increase their electrical potential energy = current

EMF • Depends on – Magnitude of B-field – Length of wire in B-field – Velocity of wire in B-field

Generators • https: //www. youtube. com/watch? v=rn. PEtw Qtm. GQ

Generators • Invented by Faraday • Converts mechanical energy to electrical energy • Wire loops wrapped around iron is placed in a strong B-field. • The iron makes B-field stronger • Iron + wire loops = armature • Increasing loops will increase EMF

• Connecting the generator to a circuit and the induced EMF will produce an electric current. • Generators and motors are almost identical. • Generators convert mechanical energy to electrical energy • http: //phet. colorado. edu/en/simulation/faraday • Motors convert electrical energy into kinetic energy

Lenz’s Law • Induced current flows in a direction to oppose the change that produced it.

• If a generator produces a small current, then the opposing force will be small and the armature will be easy to turn.

Transformers • Device used to increase or decrease AC voltage • Change voltages without losing a lot of energy

• Has 2 cells that are insulated from each other, but wound around the same iron core. • Primary Coil and Secondary Coil • When primary coil is connected to AC voltage, the changing current creates a varying B-field. • The B-field is carried through the iron core to the secondary coil. • In the secondary coil, the B-field causes a varying EMF • Mutual Inductance • https: //www. youtube. com/watch? v=Vucso. Eh. B 0 NA

Exit Slip • In your own words, describe how a generator works using a fuel source we talked about today (coal, hydro, etc. ). Include key words: mechanical energy, current, magnetic field, induce.