Assessment Questions 1-8

Generating electric current Electric current creates a magnetic field LT #2: Demonstrate and explain that an electric current flowing in a wire will create a magnetic field around that wire (electromagnetic effect) [Motors] A magnetic field can be used to produce an electric current = electromagnetic Induction = generator effect LT #3: Demonstrate and explain that moving a magnet near a wire will cause an electric current to flow in the wire (the generator effect) [Generators]

1. How is voltage induced in a conductor? Conductors are materials through which charge can flow easily (metal wires) Voltage is induced in a conductor by a changing magnetic field. So if you move a magnet near a conductor electric current is generated

2. Name two types of generators. AC = alternating current; charges flow in one direction then reverse direction & converts mechanical energy into electrical energy LT #1: Demonstrate and explain that an electric current flowing in a wire will create a magnetic field around that wire (electromagnetic effect) DC = direct current; the current that leaves the generator flows only in one direction Most power plants use AC because sending power over long distances & DC causes too much heat in wires

3. How does a transformer work? 1) A transformer increases or decreases voltage and current of 2 linked AC circuits 2) It changes voltage and current by generating a changing magnetic field in one coil. 3) This field then induces a current in a nearby coil with a different # of turns. 4) We need transformers to step up power to send it over long distances & step down power to make it safe to use in homes

4. Name the 6 sources of electrical energy in the United States. Coal Nuclear power Water = hydroelectric Wind Natural gas Petroleum

5. How can water be used to create electrical energy? Water can turn a turbine (PE  KE mechanical) The turbine turns an axle of a generator & produces electricity (mechanical  electrical) LT #1: Describe a situation where energy is transformed from one form to another.

6. What is the connection between Faraday’s law & the generation of electrical energy? Faraday’s law = a voltage is induced in a conductor by a changing magnetic field The relative motion of a magnet & a coil of wire will cause charges to flow in the wire generating electric current and electrical energy

7. How are AC & DC alike? How are they different? Both produce electric current by rotation of wire coil in a magnetic field In a DC generator current only flows in one direction

8. Why can’t we use electrical energy directly from a high voltage line? We’d fry! High voltages are dangerous & household devices are designed to use much lower voltages