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Electricity & Magnetism

Electricity & Magnetism. The Atom. 3 Subatomic Particles. 1. Proton: (+), nucleus. 2. Neutron: neutral, nucleus. 3. Electron: (-), outside. Electrons are free-moving (can be lost or gained). Electrical Forces. Law of Repulsion: Like charges repel each other.

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Electricity & Magnetism

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  1. Electricity & Magnetism

  2. The Atom 3 Subatomic Particles 1. Proton: (+), nucleus 2. Neutron: neutral, nucleus 3. Electron: (-), outside Electrons are free-moving (can be lost or gained)

  3. Electrical Forces Law of Repulsion: Like charges repel each other Law of Attraction: Opposite charges attract each other

  4. Attraction vs. Repulsion Opposites attract Likes repel

  5. Electrical Field Region around a charged particle where the force is noticeable Strongest near the charged particle.

  6. Ex) Lightning Electricity Energy created by electrons moving from one place to another. Static Electricity: build up of electrons Click hear for more information

  7. Conductors and Insulators: • Conductors allow charges to flow easily. • Examples include copper, silver, and aluminum. • Insulatorsdo not allow charges to flow easily • Examples include glass, plastic, and rubber CopperWire Rubber insulation

  8. Wires carry an electrical charge. Copper wire covered in rubber insulation Insulation (Myelin Sheath,fatty tissue) The “human” wiring system: The neuron (nerve cell) Wires (nerve fibers)

  9. Battery + A battery uses chemical energy to move electrical charges. -

  10. Electric current in a circuit + Circuits flow in a circular path

  11. Energy in a Circuit... is similar to water through pipes We will learn how to measure the energy in a circuit and how... and current, voltage, are related. resistance

  12. Warm up- January 10Page E.2 • List which objects make longitudinal waves. • Tuning fork • Slinky • Laser • Prism

  13. Ohm’s Law page E.7

  14. Volts Measurement of energy IF = 1.5 volts ?V 3.0V 1.5V

  15. Voltage: The “push” that makes electrons move; a measure of “potential difference.” Unit: volt Symbol: “V” Potential Energy (height) 1.5 V Potential Difference 1.5 Meters 0.0 V To Lower Energy The potential difference (voltage) is 1.5 V.

  16. The higher the energy, the greater the voltage (potential difference). Voltage 3.0 V GreaterPotential Difference Higher Potential energy (height) 3.0 Meters 0.0 V The potential difference (voltage) is 3.0 V. To Lower Energy

  17. Current: the flow of electrons through a wire • Unit: ampere or amp • Symbol: “I” + How fast is this water coming out? How fast (speed) is the electricity flowing through these wires?

  18. TYPES of CURRENT Direct Current (DC) flows in one direction. Alternating Current (AC)flows back and forth.

  19. RESISTANCE Which of the pipes below would allow water out faster? The smaller pipe would have more resistance to the flow.

  20. Resistance Resistance: opposition to the flow of electricity. Unit: ohm  Symbol: “R”

  21. Match the word on the left to the phrase on the right. Resistance How Fast? Ohms  or R Current How much? AMPS (I) Voltage How much is it slowed down? Volts (V)

  22. V I = R Ohm's Law Current (amp) Voltage (volt) Resistance (ohm) Ohm's Law

  23. What is the current of a light with a 90 ohms resistance in it and plugged into a 120 volt outlet?

  24. How many amps of current flow through a circuit that includes a 9 volt battery and a bulb with a resistance of 12 ohms?

  25. A lamp operates at 116 volts with a current of 30 amps. What is the lamp’s resistance?

  26. A radio operates with a potential difference of 9 V. The radio uses 0.9 watt of power. How much current does the radio use?

  27. Chemical Energy Energy Conversions in a Simple Circuit Battery converts Chemical Energy into... Electrical Energy If you add a light bulb in the circuit, electrical energy is converted into... Light Energy

  28. Open Circuit + Light will not go on because the wire isnot connectedto the battery;no current will flow.

  29. Closed Circuit + Light bulb turns on because the electrical current can now flow through the complete circuit.

  30. + Circuit Diagrams • Wire • Power Source • Bulb • Resistance • Switch open closed

  31. Types of Circuits What is the difference between the wiring?

  32. + Series Circuits If this light bulb does not turn on, Burned out light bulb This is because the circuit is broken here; neither light bulb will turn on. so the current can’t flow to this bulb here.

  33. + Parallel Circuits Current divides and has more than one path.

  34. + Parallel Circuits The current divides because it has more than one path to flow. Even though the path is stopped, the other light turns on because its circuit is not broken. Burned out light bulb Your house is wired with parallel circuits. Why do you think this is so?

  35. Electrical Power Power is measured in Watts Power = current x voltage Watts = amps x volts P = I x V If a CD player uses 4.5 V with .2 current, what is the power it uses? ? P = .2 A x 4.5 V P = I = .2 A P = .9 Watts V = 4.5 V

  36. Electrical Energy Is measured in kilowatt-hours Kilo means 1000x Energy = power x time (hr) E = kW x h You use your hairdryer for 10 minutes everyday. The hairdryer uses 1000 kilowatts. How many kilowatt-hours does your hairdryer use in 6 days? E = E = 1000 kW x 1 hr kW = 1000 kW 1000 kW 6 x 10 = 60 min or 1 hr t =

  37. Go to the web site by clicking on the circle. Do the following: 1. Intro 2. Static Charge 3. Moving Charge 4. Circuits Click Here for Internet Activity http://www.explorescience.com/activities/Activity_page.cfm?ActivityID=59

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