Sections
Glossary
Glossary
- AC current
- current that fluctuates sinusoidally with time, expressed as I = I0 sin 2πft, where I is the current at time t, I0 is the peak current, and f is the frequency in hertz
- AC voltage
- voltage that fluctuates sinusoidally with time, expressed as V = V0 sin 2πft, where V is the voltage at time t, V0 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 = ΔQ/Δt
- 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, , where I0 is the peak current, in an AC system
- rms voltage
- the root mean square of the voltage, , where V0 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