Definitions for

**"Time constant"****Related Terms:**Rise time, Decay time, Dv/dt, Settling time, Surge current, Duty cycle, Pulse , Input impedance, Impedance, Transient, Steady state, Amp hour, Amperage, Input resistance, Fall time, Peak inverse voltage, Inductive load, Vom, Voltage drop, Output impedance, Response time, Resistive load, Reset time, Ohm's law, Ohms law, Quality factor, Amp , Ammeter, Quiescent current, Voltage regulation, Alternating current, Load regulation, Ohm, Negative resistance, Internal resistance, Short-circuit current, Nominal impedance, Bias current, Ampère hour, Pulse width, Peak current, Current , Inrush current, Operating voltage, I-v curve, Choke, Ohms, Ferroresonance, Amperes, Characteristic impedance

The time required for a thermistor to indicate 63 % of a step change in temperature.

time taken to charge a capacitor to a specified voltage

The time required for an instrument to register 63.2% of an instantaneous change in the measured parameter.

The time in which an exponential process is 63% complete. For a pneumatic system characterized by a single compliance, C, and a single resistance, R, the time constant is the product RxC.

of a quantity that vary exponentially with time, the time taken for a quantity to vary by 63% of the full extent of the charge.

Time it takes a change in membrane potential to reach 63% of its final value or the time it takes for it to decay to 37% of its peak value. It determines how long a synaptic signal lasts = exp. func [membrane resistance (rm) * membrane capacitance (cm)

(electronics) the time required for the current or voltage in a circuit to rise or fall exponentially through approximately 63 per cent of its amplitude

the ratio of the inductance of a circuit in henries to its resistance in ohms

The length of time required for the output of a transducer to rise to 63.2 percent of its final value as a result of a step change in the measurand.

The value "T" in an exponential term A(-t/T). For the output of a first-order system forced by a step or an impulse, T is the time required to complete 63.2% of the total rise or decay. For higher order systems, there is a time constant for each of the first-order components of the process.

At any instant of a response to a step or impulse, the time constant (T) is the quotient of the instantaneous rate of change divided into the change still to be completed. For the output of a first-order system, T is the time required to complete 62.3% of the total rise or decay occurring as a result of the step or impulse.

A measure of the rate of buildup and decay of a localized potential; equal to the product of the resistance and capacitance of the membrane.

In a circuit that has reactance, the time it takes for the current or voltage to substantially stabilize in the circuit when the voltage or current is changing.

The time required to complete 63.2% of the total rise or decay after a step change of input. It is derived from the exponential response e-t/T where t is time and T is the time constant

Time required for an exponential quantity to change by an amount equal to 63.2 percent of the total change that can occur.

The time required for an electromagnetic field to decay to a value of 1/e of the original value. In time-domain electromagnetic data, the time constant is proportional to the size and conductance of a tabular conductive body. Also called the decay constant.

The time required for an instrument to register 63.2% of a step change in the variable being measured.

The time in seconds required for an analog system to record 63 percent of the change that actually occurred from one signal level to another.

(Also called lag coefficient.) Generally, the time required for an instrument to indicate a given percentage of the final reading resulting from an input signal; the relaxation time of an instrument. In the general case for instruments such as thermometers, with responses exponential in character to step changes in an applied signal, the time constant is equal to the time required for the instrument to indicate 63.2% of the total change, that is, the time to respond to all but 1/ of the original signal change.

Expresses the decay, with time, of a brief local change of potential. Is related to resistance and capacitance of membrane: = × .

A fixed time interval set by R, C, and/or L values that determins the time response of a circuit.

() Time required for a capacitor in an RC circuit to charge to 63% of the remaining potential across the circuit. Also time required for current to reach 63% of maximum value in an RL circuit. Time constant of an RC circuit is the product of R and C. Time constant of an RL circuit is equal to inductance divided by resistance.

In physics and engineering, the time constant usually denoted by the Greek letter \tau, (tau), characterizes the frequency response of a first-order, linear time-invariant (LTI) system. Examples include electrical RC circuits and RL circuits. It is also used to characterize the frequency response of various signal processing systems – magnetic tapes, radio transmitters and receivers, record cutting and replay equipment, and digital filters – which can be modeled or approximated by first-order LTI systems.