ASVAB-ELECTRONICS

Ohm (Ω)

Unit of resistance.

Volt (V)

Unit of electrical pressure. 

Ampere (A)

Current flow.

Watt (W)

Power used.

Coulomb (C)

Charge. 

Hertz (Hz)

Frequency cycles per sec.

Frequency

How many cycles per second.

Alternating Current (AC)

Changes direction.

Direct Current (DC)

Flows one way only.

Farad (F)

Capacitance unit.

Henry (H)

Inductance unit.

Open Circuit

Path broken.

Closed Circuit

Path complete.

Load

Device using electricity.

Ground

Safe discharge path.

Short Circuit

Unintended low resistance path. 

Polarity

Current direction.

Resistor

Limits current.

Capacitor

Stores energy.

Inductor

Magnetic energy storage.

Diode

One-way current.

Transistor

Switch/amplifier.

Rectifier

AC to DC.

Relay

Remote switch.

Filter

Removes voltage variations.

Fuse/Breaker

Safety device

Transformer

Changes voltage levels.

Conductor

Allows flow.

Insulator

Blocks current.

Semiconductor

Half conductor, half insulator.

Ohm's Law

V = I × R

Current (I)

I = V / R

Resistance (R)

R = V / I

Power

P = V × I or P = I² × R or P = V² / R

Charge (Q)

Q = I × t

Series Circuit

R_total = R1 + R2 + R3

Parallel Circuit

1/R_total = 1/R1 + 1/R2 + 1/R3