Sections

Glossary
# Glossary

- AC current
- current that fluctuates sinusoidally with time, expressed as
*I =**I*_{0}sin 2*πft*, where*I*is the current at time*t,**I*_{0}is the peak current, and*f*is the frequency in hertz

- AC voltage
- voltage that fluctuates sinusoidally with time, expressed as
*V =**V*_{0}sin 2*πft*, where*V*is the voltage at time*t,**V*_{0}is the peak voltage, and*f*is the frequency in hertz

- alternating current (AC)
- the flow of electric charge that periodically reverses direction

- ampere
- (amp) the SI unit for current; 1 A = 1 C/s

- direct current (DC)
- the flow of electric charge in only one direction

- drift velocity
- the average velocity at which free charges flow in response to an electric field

- electric current
- the rate at which charge flows,
*I*= Δ*Q*/Δ*t*

- electric power
- the rate at which electrical energy is supplied by a source or dissipated by a device; it is the product of current times voltage

- microshock sensitive
- a condition in which a person's skin resistance is bypassed, possibly by a medical procedure, rendering the person vulnerable to electrical shock at currents about 1/1000 the normally required level

- ohm
- the unit of resistance, given by 1Ω = 1 V/A

- Ohm's law
- an empirical relation stating that the current
*I*is proportional to the potential difference*V*,*∝ V*; it is often written as*I = V/R*, where*R*is the resistance

- ohmic
- a type of a material for which Ohm's law is valid

- resistance
- the electric property that impedes current; for ohmic materials, it is the ratio of voltage to current,
*R = V/I*

- resistivity
- an intrinsic property of a material, independent of its shape or size, directly proportional to the resistance, denoted by
*ρ*

- rms current
- the root mean square of the current, ${I}_{\text{rms}}={I}_{0}/\sqrt{2}$ , where
*I*_{0}is the peak current, in an AC system

- rms voltage
- the root mean square of the voltage, ${V}_{\text{rms}}={V}_{0}/\sqrt{2}$ , where
*V*_{0}is the peak voltage, in an AC system

- shock hazard
- when electric current passes through a person

- short circuit
- also known as a “short,” a low-resistance path between terminals of a voltage source

- simple circuit
- a circuit with a single voltage source and a single resistor

- temperature coefficient of resistivity
- an empirical quantity, denoted by
*α*, which describes the change in resistance or resistivity of a material with temperature

- thermal hazard
- a hazard in which electric current causes undesired thermal effects