1 Electricity

2 Electrons + + Negative Charge ELECTRICITY comes from the electrons in an atom.

3 Electricity Flow of electricity through wires Static Electricity Electrical Current Build-up of electrical charge

4 Static Electricity Lightning Zap! Electricity exists naturally in nature… For example:

5 Electric Charge The source of static in lightning and shocks is electric charge Most objects tend to be

6 Neutral ObjectCharged Object Net Charge: Net Charge of Objects:

7 Opposites Attract + - Same Charges Repel

8 How do balloons stick to walls? Negative charges in the wall repel from the balloon. 1. Rub a balloon on a sweater to “charge it up.” The balloon sticks because the positive charges left over are attracted to the balloon.

9 The Electroscope 2 Gold “leaves” Metal rod Electricity can move down the metal rod to the two gold leaves.

10 The Electroscope When a rubber comb with a build-up of static electricity is touched to the rod builds up on both sides of the gold strip. Since the charge of the leaves are both negative the two sides of the strip repel one another.-- …the electric charge travels down the rod AND...

11 A battery uses chemical energy to move electrical charges.

12 + Circuits flow in a circular path

13 Measurement of energy IF = 1.5 volts 1.5V 3.0V ?V

V 0.0 V The potential difference (voltage) is 1.5 V. Potential Energy (height) To Lower Energy Potential Difference Voltage and is a measure of “potential difference.” The unit for voltage is volts (V) 1.5 Meters

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

16 Current rate is the rate of the flow of an electrical charge. + How fast is this water coming out? How fast (speed) is the electricity flowing through these wires? rateCURRENT The rate that the electricity flows is called CURRENT CURRENT is measured in AMPS (I).

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

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

19 Resistance is measured in ohms. 

20 to Electrical Current Which of the following do you think would be most resistant to electrical current? Plastic Rubber Glas s

21 These materials allow electrical charge (current) to move easily through them. They have little resistance to the flow of electrical current. They are

22 These materials do not allow electrical charges (current) to move easily through them. They have a strong resistance to the flow of electrical current. Plastic Rubber Glass They are

23 Conductors and Insulators: Insulators do not allow charges to flow easily –Examples include glass, plastic, and rubber Copper Wire Conductors allow charges to flow easily. –Examples include copper, silver, and aluminum. Rubber insulation

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

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

26 We can use this formula to figure out volts, current (amps) and resistance.

27 Calculate the potential difference (volts) across a 3  resistor if a 0.5 A current is flowing through it. V = I x  What do you know? V = I =  = 0.5 A 3  ? V = 3  0.5 Ax 1.5 V = V

28 A radio with a resistance of 240  is plugged into a 120 V outlet. What is the current flowing from the outlet? V = I x  What do you know? V = I =  = 120 V 240  ? 120 V = 240  Ix 0.5 amps = I 1 or V/ 