Chapter 10Current Electricity

10.1 - Electricity and Electric CircuitsCurrent Electricity - electric charges flowing in a circuit through a conductor in a controlled way

The parts of an electric circuit

Energy source

Load

Switch

Wires

ex: battery

ex: light bulb

ex: on/off switch

ex: completes the path and joins everything together

Energy Sources of Circuits

Energy is measured in JOULES (J)

Electrical energy is provided by electrons

Sources of Electrical Energy

Electric cell - converts chemical energy into electrical energy (battery)

Two kinds: Primary Cells and Secondary Cells

Primary cells can’t be recharge; Secondary cells can be recharged

The Load in Circuits

Converts electrical energy into another form of energy.

ex: light from a light bulb; heat from a filament in a toaster; motor in a saw

The Pathway in a Circuit

Conducting wires are used to create a path in a circuit

Copper is the most common conductor (wire) used

Electric Circuit Diagrams and Symbols

Circuit Diagram - represents an electric circuit using standard symbols

Homework: Read 10.1 in your textbook and do the following questions pg. 305 - # 1 - 12

10.2 - Electric CurrentElectric Current (I)- flow of electric charges through a circuit

Like a flowing riverMeasured in amperes (A)

Amount of charge through a circuit at a given time.

I (current in amperes); Q (charge in Coulombs); t (time in seconds)

Direction of Electric Current

Flows from positive to negative terminal

Flows from negative to positive terminal

Original thought about electricity flow

Known as conventional current

Modern day electricity flow (because electrons are moving)

Known as electron flow

Direct current (DC)

Alternating current (AC)

Electric flow from cells (ex: watch batteries, etc.)

Electron flow reverses/alternates (electricity in your home)

Series and Parallel Circuits

Series circuits - current goes through each device in sequence

Parallel circuits - current is split up and some of it goes through each device

Measuring Electric Current

Ammeter measures electric current current at a given point in the circuitMeasured in amperes (A) and milliamperes (mA)

Homework: Read 10.2 in your textbook and do the following questions pg. 309 - # 1 - 15

10.3 - Electrical Potential Difference (Voltage)Voltage (V)- the change in electric potential energy per coulomb of charge

Measured in volts (V)

Measuring Voltage

Measured using VOLTMETER

Symbol:

Connect voltmeter in PARALLEL to a battery/cell, load, resistor, etc.

Cells in Series

The voltage of cells/batteries in series ADD

ex: 2 - 9V batteries in series gives 18V

Homework: Read 10.3 in your textbook and do the following questions pg. 314 - # 3 - 12

Cells in Parallel

Voltages DO NOT add up

ex: 2 - 9V batteries in parallel gives 9V

10.4 - Resistors and Ohm’s Lawresistor - resists/opposes the flow of electrical current

Measured in ohms (Ω)

Circuit Symbol:

Resistor code:

Ohm’s Law

The ratio of the voltage across a conductor to the current through the conductor

Can also be written in terms of voltage:

Sample Problems

Sample Problems

Homework: Read 10.4 in your textbook and do the following questions pg. 319 - # 2 - 7, 10

10.5 - Resistors in Series and Parallel Circuits

Sample Problems

Homework: Read 10.5 in your textbook and do the following questions pg. 325 - # 2 - 8