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Electricity and Magnetism CRCT review. just like gravity A force that depends on: Size (mass or charge of objects) Distance between the centers.

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Presentation on theme: "Electricity and Magnetism CRCT review. just like gravity A force that depends on: Size (mass or charge of objects) Distance between the centers."— Presentation transcript:

1 Electricity and Magnetism CRCT review

2 just like gravity A force that depends on: Size (mass or charge of objects) Distance between the centers

3 What particle? carries positive charge in the atom? Where is it? carries negative charge in the atom? Where is it? has no charge in the atom? Where is it?

4 static electricity Electric charges are separated. More of either protons or electrons in one place. How? Move electrons

5 Ways to move electrons friction – rub them from one object to another conduction – electrons flow from touching objects induction – electrons move in response to electric field without objects touching

6 Electric current What is electric current? What does an electric current cause? What is caused when the current is changing?

7 magnets Electrons with same spin line up and create magnetic domains. Permanent magnets: lots of aligned domains Cobalt, nickel and iron make good permanent magnets.

8 magnetic properties Always has both north and south pole Cut in half = two whole magnets

9 Earth’s magnetic poles http://hyperphysics.phy-astr.gsu.edu/ hbase/magnetic/imgmag/mearthbar.gif

10 solenoid Coil of wire

11 electromagnet solenoid wrapped around an iron core The magnetic field inside iron magnifies the solenoid’s field http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/imgmag/sol3.gif

12 Stronger electromagnet More loops More current

13 Works other way too! Move the magnet to get an electric current. (Section 3) http://media.web.britannica.com/eb-media http://media.web.britannica.com/eb-media /73/63373-004-CDB7E548.gif

14 Electric motor An alternating current causes a magnet to spin The magnet is attached to some mechanical device that spins (ex: fan blade)

15 Electric generator A spinning magnet causes an alternating current.

16 Circuits energy source load wires

17 Circuits series lined up like train cars one current path same current everywhere parallel branches more than one current path same voltage on each branch

18 Schematic of a DC circuit with three resistor in series http:// www.school-for-champions.com/science/dc_circuits.htm

19 Schematic of a DC circuit with three resistor in parallel http:// www.school-for-champions.com/science/dc_circuits.htm

20 V = IR What happens to current if voltage increases? What happens to current if resistance increases?

21 SI units electric potential (aka: voltage) = volt (V) current = ampere (A) resistance = ohm (Ω)

22 Decrease resistance in a wire shorter wire thicker wire cool the wire


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