Voltage in Electrical Systems

Unit 4 Voltage Pages  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