Glossary#
- Accuracy
The average variation in the bias between measurements and truth. Good measurements are both accurate and precise.
- Ammeter
A device that measures electrical current.
- Burden Voltage
The voltage drop that occurs through the test equipment device. For shunt ammeters, the burden voltage includes the voltage across the shunt resistor, connectors, fuses, and any additional resistance in the device.
- Current
The flow of electric charge per time from positive voltage to negative voltage, measured in amperes (A), often called amps. One amp is one coulomb of charge flowing per second. One coulomb is approximately 6.242 x 10¹⁸ electrons, but electric current is defined opposite to the electron flow.
- Energy
The total power exerted over time, measured in joules (J). Energy is the time integral of power.
- Insertion Loss
The loss in signal power due to a device in the signal path, most commonly used in reference to radio frequency (RF) or telecommunications. See Burden Voltage.
- Multimeter
A multifunction device that usually incorporates a voltmeter and shunt ammeter, at a minimum. A standard multimeter supports only one measurement quantity at a time.
- Ohm’s Law
The equation that relates voltage, current and resistance: V = I * R
- Oscilloscope
A device that graphically displays one or more signals, usually voltages, varying over time as a two-dimensional plot with time on the x-axis and the signal on the y-axis.
- Power
The time-rate of doing work, measured in watts (W). Power is voltage multiplied by current.
- Precision
The amount of variation between measurements of the same value relative to each other. Good measurements are both accurate and precise.
- Resistance
The quantity of opposition to the flow of electric current.
- Shunt Ammeter
An ammeter that measures the voltage across a resistor, and then uses Ohm’s Law to compute current.
- Shunt Resistor
The resistor used by “Shunt Ammeters” to detect current using Ohm’s Law: I = V / R. Given a known R and a measured V, the ammeter computes I.
- Universal Serial Bus (USB)
The now ubiquitous standard for connecting computers and peripherals. Joulescope connects to the host computer using USB 2.0 high-speed operating at 480 Mbps.
- Voltage
The electric potential difference, measured in volts (V).
- Voltmeter
A device that measures electrical voltage.