1. Warm-up
Is it possible to create a circuit with wires, but no battery or other electrical power supply?

2. Electricity from Magnetism

3. Current
Moving charges (a current) creates a magnetic field.

4. Current without a battery
A current results when a closed electric circuit moves with respect to a magnet field.
This process is called Electromagnetic Induction (Inducing a current in a circuit by changing the magnetic field that passes through the circuit.)
The magnet or the circuit need to be moving to produce a current

6. Faraday’s Law
The induced voltage in a coil is proportional to the product of the number of loops and rate at which the magnetic field changes within the loops

7. Generators A machine that uses a magnetic field to produce electricity
spinning a wire coil in the magnetic field.
Uses wind, water, or steam
Mechanical Energy is converted to Electrical Energy
Produces Alternating Current

9. Transformers
Since we use AC current in our homes, we need transformers to “step down” the voltage between the power plant and our home.
Alter the voltage and current

10. 𝑉 𝑝 𝐼 𝑝 = 𝑉 𝑠 𝐼 𝑠 or 𝑉 𝑝 𝑁 𝑝 = 𝑉 𝑠 𝑁 𝑠
Transformers
Power that goes in = Power that comes out
P=VI (voltage and current are inversely related)
𝑉 𝑝 𝐼 𝑝 = 𝑉 𝑠 𝐼 𝑠 or 𝑉 𝑝 𝑁 𝑝 = 𝑉 𝑠 𝑁 𝑠

11. Transformers

12. Transformer Efficiency
Ideal Transformers would be 100% efficient (Power in = Power out), however, most transformers are only90-99% efficient.
Power is lost because of the small currents induced by changing magnetic field in the transformer’s iron core and because of resistance in the wires of the windings. (aka. FRICTION)