ASVAB Electronic Information General

Current, voltage, and resistance

Think of electricity like a water in a pipe. Voltage is the pressure pushing it, current is how much flows, and resistance is anything that slows the flow done

Current

Abbreviated as I and is measured in Amperes (A). This is the flow of electric charge

Voltage

Measured in Volts (V). This is the push that moves the current

Resistance

Measured in Ohms and is the opposition to the current

Power

Measured in Watts and is how fast energy is used. Higher wattage means more energy used. Power in electronics equals Voltage times Current

Ohm’s law

Connects voltage, current and resistance. If you know any two, you can find the third. Current equals Voltage divided by Resistance and Voltage equals Current times Resistance. Resistance equals Voltage divided by Current

Series Circuit

There is one path in this kind of circuit. Resistance adds up and the same current flows through each part. Here, resistance equals Resistance 1 plus Resistance 2

Parallel Circuit

Current splits between two paths so the total resistance is lower than the smallest single resistor. Here, 1/Resistance equals 1/Resistance 1 plus 1/Resistance 2.

Conductor

A material current flows through easily such as copper, silver or aluminum

Insulator

A material that blocks current such as rubber, glass or plastic

Semiconductor

A material such as silicon or germanium that conducts better than an insulator but not as well as a conductor. Used to make Diodes and Transistors

Direct current

Current that flows in one direction, as from a battery

Alternating current

Current that reverses direction many times a second, as in household outlets

Frequency

How many times AC changes direction each second, measured in hertz (Hz). U.S Household power is 60hz

Rectifier

A device that changes AC into DC

Watt-hour

A unit of energy: power used over time. A 100-watt bulb left on for 10 hours used 1,000 watt-hours (1kilowatt-hour).

Ground

A safe path that carries stray current into the earth

Resistor

Limits current

Capacitor

Stores and releases electric charge

Diode

Lets current flow in only one direction

Transistor

Switches or amplifies a signal

Fuse

Breaks the circuit when current is too high