Voltage in Electrical Systems

Unit 4 Voltage Pages 71-76 Voltage source Conductors Control element Electrical appliance Electrical loads Electrical circuit Direct current Alternating current Volts

Primary cells Secondary cells

Electrode Cathode

Anode In series Electron

Frequency Voltmeter

Unit 4 Voltage Pages 77

Answer # 1-8

Electrical Systems

Made up of voltage sources, conductors, control elements, and appliances and machines

Batteries/generators, wire/circuits, switches, lights/appliance

Conductor

Any material that allows the movement of

electrical energy through it

Control Element

Wall switch Volume on a radio Variable speed switch

Electrical Load

Motor Light Bulb Appliance

Electrical Circuit

Closed path made by connecting voltage sources, control elements, and electrical loads

AC vs. DC Electricity

AC – Alternating Current

DC – Direct Current

AC Electric charges move

back and forth many times a second in the wire

DC

Electric charges in wires always move in one direction

AC Produced by alternators

DC

Produced by batteries

Dry-cell batteries A chemical produces the voltage

Wet-cell batteries

Contain a liquid electrolyte Usually a strong acid Used to start engines because they

can deliver a lot of power

Primary cells

Not easily recharged

Secondary cells

Easily recharged

The ability to recharge a battery allows us to group these chemical

producers of voltage into two classes

How are DC Voltage sources connected?

The output of a voltage source comes from two terminals called electrodes

DC sources normally have two electrodes

A Positive and a negative

How are DC Voltage sources connected?

Electrons move in the circuit as if they were flowing out of the negative electrode and into the positive

The negative electrode is called the “cathode”

The positive electrode is called the “anode”

How do we produce higher voltage?

DC voltage sources can be added together in series

Positive source must be connected to the negative terminal of the other source in succession

If connected in an opposing manner it will sometimes cause battery damage

What makes up a simple DC Circuit?

How do we make schematics? Symbols:

Battery

Light bulb

Switch

Conductors

AC Voltage

AC Voltage changes direction about 60 times each second

This rate of change is called the frequency

Frequency is measured in cycles per second or hertz

How do we measure voltage

Modern electronics have made digital voltmeters available

Oscilloscopes are used often in analyzing, testing, and troubleshooting electrical systems and circuits

They can also be used as voltmeters