Electricity 1.notebook. May 04, 2016 ELECTRICITY. objects.

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1 ELECTRICITY is objects. 1

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7 Insulators and Conductors You should now know that electricity. 1. Electrical Insulator - Any substance in which Examples: 7

8 If atoms in an become charged with, these remain on the until. - They do not move ( ) 2. Electrical Conductor - Any substance in which Examples: If atoms in a become charged with, these can move and along the of the conductor. 8

9 After cleaning coffee tables, they seem to always get dusty, but kitchen sinks and water taps don t. Why? When a has all of its removed, it is said to be or. There are 4 main methods of discharging. 9

10 1. Grounding When a is connected to the ( ) using a, it transfers its to the earth and becomes in charge. Examples: 10

11 2. Discharge at a point The shape of a affects the at which it becomes. shapes retain charges. shapes lose charge. This happens because charges built up at the actually get. 11

12 3. Exposure to Air If there is enough in the air, excess will leave objects by (g). 4. Sparks and Lightning Once a certain ( ) have built up, and an object any more charges, the that the will actually through the to the to try and make it to the. is really just a giant spark. 12

13 1. What is the purpose of a lightning rod? 2. Why is lightning less common in the downtown areas o large cities like Toronto? 3. Where is the safest place to be when lightning is present? 13

14 The Simple Electric Circuit The movement of (e ) is called When moves through a controlled path we call it an. Electric are used to into other useful forms of. o 14

15 Schematics A schematic, or schematic diagram, is a representation of the rather than realistic pictures. 15

16 Simple Electric Circuit A couple of terms you need... Series Parallel 16

17 Praccing Schemac Diagrams 1. 2 cells in series, switch, 1 bulb 2. 2 cells in parallel, switch, 2 bulbs in series 17

18 3. 1 cell, 2 bulbs in series, switch, voltmeter across one of the bulbs 4. 1 cell, 2 bulbs in parallel, switch, 1 ammeter between the bulbs 18

19 5. 3 cells in series, switch, 4 bulbs in series, voltmeter across 1 bulb V baeries in parallel, 2 bulbs series, 1 motor in parallel with the bulbs, 1 switch to control only the bulbs. ` 19

20 Draw a circuit with 2 6 V batteries in parallel with each other. They are in turn attached to a light bulb, a motor, and a resistor all in parallel with each other. A second bulb is in series with all the other loads. An ammeter measures the current through the motor and resistor but not the light bulbs. There is a switch to control only the motor. A voltmeter measures the voltage of the resistor. There is also a fuse which protects the motor. Electric Potential Electrons (e ) carry. The energy has the to do work. This energy is called 20

21 Because electrons are we measure the energy carried by a and call the energy Measurement Symbol Unit Symbol 21

22 Life of an Electron 1. Start life at the terminal of a cell with no 2. e moves toward the terminal of the cell collecting as it goes. The battery gives the e of energy. 22

23 3. If we measure the (Voltage) the cell we see: If the e finished with 1.5 units and started with 0 units then: Difference = = 1.5 V 4. e runs with until it reaches a. 5. e enters light with. e to bulb (heat/light) and leaves with. Difference = = 23

24 Electric Current Electric current is a measurement of When we measure current we are measuring 24

25 The symbol for current is The unit of measurement for current is Electric Potential and Electric Current Problems Recall: Electric is the amount of energy that a group of electrons (coulomb) carry. Therefore: 25

26 Electric current is the (coulomb) passing a point every second. Therefore: Problem 1. If 42 J of chemical energy is available in a battery, and that energy is given to 7.0 C of electrons what is the electric potential difference (voltage) of the battery? 26

27 Problem 2. If 240 C of charge pass a point in a circuit in 5 minutes, what is the current at that point? 3. How much electric potential energy is available in a circuit if 8.5 C of charge pass through a 12 V battery? 27

28 4. In a 3.25 A circuit, how long does it take 4.5 C of charge to move through the circuit? 5. In a circuit with a 9 V battery, 3 A of current moves through the circuit in 2 sec. How much energy do the electrons have? 28