Ohm’s Law: The equation that you use to calculate voltage, current, resis-
tance, or power.open circuit: A circuit in which a wire is disconnected. Therefore, no current
is able to flow. See alsoclosed circuit.open position: A switch position that stops current from flowing. See also
closed position.operational amplifier:Also called op amp.An integrated circuit that contains
transistors and other components. An op amp provides uniform amplification
over a wider range of frequencies than a single-transistor amplifier.oscillator: A circuit that generates waveforms. See alsowaveform.oscilloscope:An electronic device used to measure voltage, frequency, and
other parameters for waveforms.p-type semiconductor: A semiconductor to which contaminants are added
that cause it to contain fewer electrons than a pure semiconductor.pad: Contact points on a circuit board used to connect components.Phillips: Both a screw with a plus-shaped (+) slot in its head and the screw-
driver that you use with that type of screw.pn junction: The interface of two regions that contain boron and phosphorus
adjacent in a semiconductor. Transistors and diodes contain pn junctions.
See alsotransistor, diode.potentiometer: A variable resistor that allows for continual adjustment of
resistance. This adjustment can range from virtually 0 (zero) ohms to a maxi-
mum value.power: The measure in watts of the amount of work that electric current
does while running through an electrical component.proton: A positively charged particle. See alsoelectron.prototyping board: Seebreadboard.pulse: A signal that rapidly alternates between high and low.pulse width modulation: A way to control the speed of a motor by turning
voltage on and off in quick pulses. When the on intervals are longer, the
motor goes faster.386 Electronics Projects For Dummies
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