3.3+book+2


 * III. electricity from magnetism**
 * A. A magnet and a conductor, such as a wire, can be used to induce a current in the conductor**
 * 1. Key is motion**
 * 2. Electric current is induced in a conductor when the conductor moves through a magnetic field**
 * 3. Induced current - electromagnetic induction**
 * i. Generating an electric current from the motion of a conductor through a magnetic field**
 * ii. Induce a current in a conductor**
 * a.) conductor can move through magnetic field**
 * b.) magnetic itself can move**
 * iii. Coil on galvanometer - if moved up or down - current is induced without a battery or voltage source**
 * B. Direct Current (DC)**
 * 1. current consisting of charges that flow in 1 direction only**
 * 2. Edison used in 1st generating plant**
 * 3. Can alternate directions**
 * 4. Will not run transformers**
 * C. alternating currents (AC)**
 * 1. Consists of charges that move back and forth in a circuit**
 * 2. voltage can be easily raised or lowered to higher/lower voltage**
 * D. Generators**
 * 1. electric generator - device that transforms mechanical energy into electrical energy**
 * 2 . Uses motion in a magnetic field to produce an electric current**
 * 3. AC Generator**
 * i. Crank - rotates armature**
 * ii. Slip rings - attached to ends of armature**
 * iii. Armature - current induced as it rotates**
 * 4. Brush - current leaved generator thru brushed**
 * i. like electric motor**
 * ii. becomes energy source**
 * 5. Current in opposite direction on 2 sides of armature**
 * i. alternating current**
 * 6. DC Generators**
 * i. like AC generator**
 * a.) contains commentator instead of slip rings**
 * 7. Using generators**
 * i. electric companies**
 * ii. turbine instead of crank**
 * a.) large circular devices made up of many blades**
 * b.) spins as water flows by it**
 * E. Transformers**
 * 1. Device that increases or decreases voltage**
 * 2. Consists of 2 separate coils of insulated wire wrapped around an iron core**
 * i. primate coil - connected to a circuit with a voltage source and alternating current**
 * ii. Secondary coil - connected to a separate circuit that does not contain a voltage source**
 * 3. Only works if the current in the primary coil is changing**
 * 4. Wont work with a direct current**
 * 5. Step - up transformer - a transformer that increases voltage by having more loops on secondary coil**
 * 6. Step down transformer - a transformer that decreases voltage by having fewer coils on secondary coil**
 * 7. Allow safe transmission of electrical energy from generating plants to the consumer**
 * 8. in some devices - step up:**
 * i. 120 volts**
 * ii. flouresent lights**
 * iii. TVs**
 * iv. X - ray machines**
 * 9. Step down devices:**
 * i. 6 - 12 volts**
 * ii. doorbell**
 * iii. electronic games**
 * iv. portable players**
 * Quiz**
 * armature**
 * current**
 * reverses**
 * alternating**
 * 1. The primary coil is connected to a circuit with a voltage source and alternating current. Secondary coil is connected to a separate circuit that does not have a voltage source.**
 * 2. Electric motor transforms electrical energy to mechanical energy. A generator transforms mechanical energy to electrical energy**
 * 3. Generating a current from the motion of a conductor through a magnetic field**
 * 4. type of current found in the circuits of homes**
 * 5. type of current produced by a battery**
 * 6. device that transforms mechanical energy into electrical energy**
 * 7. device that increases or decreases voltage**
 * 8. device that increases voltage**
 * 9. device that decreases voltage**
 * Study Guide**
 * 4. turns the armature of a generator**
 * 6. its electric plants are small and close together**
 * 7. alternating current**
 * 9. to produce an electric current**
 * 10. electromagnetic induction**
 * 12. mechanical energy**
 * 15. transformer**
 * 17. true**
 * 19. true**
 * 20. true**
 * 21. Transformer 2: step up; transformer 1 - step down When current is produced at an electric plant, its voltage is increased so that it's transmitted efficiently through electric lines, then decreases for us in people's homes.**
 * 22. B has greatest voltage because on up side of step up transformer**
 * 24. No a transform works only if the current in the primary coil is charging. If current doesn't change the magnetic field doesn't change. No current will be induced in secondary coil.**