“time constant”的概念、定义、翻译、参考文献-科学参考

time constant

Physics

Symbol τ‎ or T. A quantity that gives a measure of the rate of discharge of a capacitor through a circuit consisting of the capacitor and a resistor. It is given by CR seconds, where C is the capacitance in farads and R is the resistance in ohms. It is the time taken for the quantity to fall to 1/e of its original value.

Chemical Engineering

A parameter that determines the dynamic path of a process to respond to a disturbance and approach a new steady state. It is a product of both capacity and resistance. A low resistance means that the final steady-state condition is reached quickly. 63.5 per cent of the final change corresponds to one time constant after the input change.

Electronics and Electrical Engineering

The time required for a unidirectional electrical quantity, such as voltage or current, to decrease to 1/e (approximately 0.368) of its initial value or to increase to (1 −1/e) (approximately 0.632) of its final value in response to a change in the electrical conditions in an electronic circuit or device. Thus at any instant following initiation of the change in electrical equilibrium, such as switching a d.c. supply voltage on or off, the instantaneous change of a quantity, V, is given by
$\frac{d V}{d t} = \frac{(V_{f} - V)}{τ}$
where V_f is the final value of the quantity and τ the time constant. In the case of a decreasing quantity V_f is usually zero and the expression becomes
$\frac{d V}{d t} = - \frac{V}{τ}$
The time constant is a measure of the speed of operation of any circuit or device; circuits that contain capacitance or inductance can have very long time constants (of about a few seconds). For example, the time constant of a circuit containing a resistance of R ohms in series with a capacitance of C farads is given by
$τ = R C seconds$
One that contains a resistance, R, in series with an inductance of L henries has a time constant given by
$τ = \frac{L}{R} seconds$

单词	time constant
释义	time constant Physics Symbol τ‎ or T. A quantity that gives a measure of the rate of discharge of a capacitor through a circuit consisting of the capacitor and a resistor. It is given by CR seconds, where C is the capacitance in farads and R is the resistance in ohms. It is the time taken for the quantity to fall to 1/e of its original value. Chemical Engineering A parameter that determines the dynamic path of a process to respond to a disturbance and approach a new steady state. It is a product of both capacity and resistance. A low resistance means that the final steady-state condition is reached quickly. 63.5 per cent of the final change corresponds to one time constant after the input change. Electronics and Electrical Engineering The time required for a unidirectional electrical quantity, such as voltage or current, to decrease to 1/e (approximately 0.368) of its initial value or to increase to (1 −1/e) (approximately 0.632) of its final value in response to a change in the electrical conditions in an electronic circuit or device. Thus at any instant following initiation of the change in electrical equilibrium, such as switching a d.c. supply voltage on or off, the instantaneous change of a quantity, V, is given by $\frac{d V}{d t} = \frac{(V_{f} - V)}{τ}$ where V_f is the final value of the quantity and τ the time constant. In the case of a decreasing quantity V_f is usually zero and the expression becomes $\frac{d V}{d t} = - \frac{V}{τ}$ The time constant is a measure of the speed of operation of any circuit or device; circuits that contain capacitance or inductance can have very long time constants (of about a few seconds). For example, the time constant of a circuit containing a resistance of R ohms in series with a capacitance of C farads is given by $τ = R C seconds$ One that contains a resistance, R, in series with an inductance of L henries has a time constant given by $τ = \frac{L}{R} seconds$
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