Electricity

Static, Currents, Circuits

1

Electrical Fields Is a force field that surrounds an electric

charge or group of chargesSimilar to force field that surrounds a mass

– gravitational field

2

Electrical FieldsElectric field has magnitude and directionVector quantity represented with electric

field lines (out from positive, in to negative)

3

Electricity that moves…

Current: The flow of electrons from one place to another.

Measured in amperes (amps)Kinetic energy

4

There are 2 types of currents:

Direct Current (DC) – Where electrons flow in the same direction in a wire.

5

There are 2 types of currents:

Alternating Current (AC) – electrons flow in different directions in a wire

6

AC vs. DC

AC/DC: What's the Difference?

7

What is Resistance?

The opposition to the flow of an electric current, producing heat.

The greater the resistance, the less current gets through.

Good conductors have low resistance.

Measured in ohms.

8

What Influences Resistance?

Material of wire – aluminum and copper have low resistance

Thickness – the thicker the wire the lower the resistance

Length – shorter wire has lower resistance

Temperature – lower temperature has lower resistance

9

Electrical Potential Energy

Energy a charge has due to its location in an electric field

Just as GPE is the work required to lift object, EPE is work done to push charge against the electric field of something else that is charged.

10

What is Voltage?

The measure of energy given to the charge flowing in a circuit.

The greater the voltage, the greater the force or “pressure” that drives the charge through the circuit.

11

Difference b/t Volts and Amps

Example – you could say that…Amps measure how much water

comes out of a hose.Volts measure how hard the water

comes out of a hose.

12

Ohm’s Law

Resistance = Voltage / Current

Ohms = Volts / Amps

13

Practice with Ohm’s Law

Ohms Volts Amps

4 100 25

15 150 10

2 30 15

9 45 5

6 48 814

CircuitsComplete path for electrons to flow (circuit)

Battery and Light bulbElectrons flow from negative terminal to

positive terminal

15

How can we control currents?

With circuits.Circuit: is a path for the flow of

electrons. We use wires.

16

Parts of a Circuit:

17

Circuits:

For electricity to flow a circuit must be closed:

18

There are 2 types of circuits:

Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off.

19

Series Circuit

20

There are 2 types of circuits:

Parallel Circuit – there are several branching paths to the components. If the circuit is broken at any one branch, only the components on that branch will turn off.

21

Parallel Circuit

22

Parallel CircuitSeries Circuit

23

Schematics of Circuits

24

Equivalent Resistance

25

Equivalent Resistance

26

Conductors vs. Insulators

Conductors – material through which electric current flows easily.

Insulators – materials through which electric current cannot move.

27

Examples

Conductors:MetalWater

Insulators:StyrofoamRubberPlasticPaper

28