1 Alternating current can be converted to current

1. Alternating current can be converted to ____ current using a ______. direct diode 2. Charges move easily through a conductor _______ but cannot move an insulator through ______. 3. Draw a series circuit with two bulbs in it.

4. transistor – semiconductor device that can be used as an amplifier or a switch 5. solenoid – 6. resistance – 7. diode – a coil of wire that produces a magnetic field when carrying an electric current opposition to the flow of electric current semiconductor device that only allows electricity to flow one direction. It can convert AC to DC. 8. static electricity – the buildup of electrical charges on an object 9. magnet – any material that attracts iron or materials which contain iron. 10. electricity - the flow of electrons

11. Draw a parallel circuit with three bulbs in it. 12. How does a circuit board work? A circuit board is a collection of hundreds of tiny circuits mounted on a “board” that together supply electric current to the various parts of an electronic device.

13. If a charged object goes near an electrically neutral surface (but doesn’t touch it), then it can be charged induction through ______. However, if there is direct conduction contact, the surface is charged by _______. 14. If three solenoids all have the same number of loops but different magnetic fields, what must be different? More iron in the core, more current (like a bigger battery), or shorter wires (less resistance)

repel 15. If two charges are the same, they will _______ each other. 16. If you rub a piece of plastic with felt, the plastic becomes charged by _____. friction 17. In a parallel circuit, no matter how many bulbs you add, they will all have the _______ brightness. same electrical discharge 18. Lightning is an example of __________; this is the loss of static electricity as charges move off an object.

semiconductor 19. Transistors and diodes are both made of ________ material. electrons 20. When an object gains or loses ______, it becomes charged. 21. Name 3 things that will decrease resistance. a. use a thicker wire b. use a shorter wire c. cool the temperature d. use a material that is a good conductor

22. Name 3 ways to make an electromagnet stronger: • • increase the number of coils in the solenoid put more iron in the core increase the current (bigger battery) use a shorter wire for less resistance 23. Name 2 ways to increase the magnetic field of a solenoid. • more coils • put an iron core in the solenoid • use more current (bigger battery)

24. Technology can be much smaller today because of 25. The law of electric charges states: 26. What is the difference between alternating and direct current? In direct current, the charges always flow in one direction. In alternating current, the charges constantly switch directions, moving back and forth.

27. What is the difference between an electric motor and a generator? Electric motor converts Electrical to Kinetic energy. Generator converts kinetic energy to electrical energy. 28. How does electromagnetic induction work? Using electromagnetic induction, you can produce an electrical current by changing a magnetic field. For example, if you move a magnet around in a coil of wire, you can produce an electric current.

29. A 100 Ω resistor is connected to a 20 V supply. What current flows through it? (Show your work and include units!) 30. Calculate the voltage across a 300 Ω resistor when a current of 0. 004 A flow through it. (Show your work and include units!) Factor in Symbol Ohm’s Law Unit Symbol for Unit 31. Resistance R Ohm Ω 32. Current I Ampere A 33. Voltage V Volts V

34. You’re putting up a set of LED lights that are a bit fragile. You’re adding them to a circuit with a brand new 9 V battery. Assuming there is no resistance from the attached ammeter or the wires, how much resistance is there in each LED light?