Subelement B: Electrical Math— Topic 14: RC Time Constants-1
Question 3-14B4
Element 3 (GROL)What is the meaning of the term “time constant of an RL circuit”? The time required for the:
Explanation
The time constant ($\tau$) of an RL circuit is a fundamental characteristic that describes the circuit's transient response. It is defined as the time required for the current flowing through the inductor to build up to approximately 63.2% of its maximum steady-state value after a voltage is applied. This exponential build-up occurs because inductors inherently oppose sudden changes in current.
Options A and D are incorrect because 36.8% represents the percentage *decay* from an initial value (e.g., current decay in an RL circuit or voltage decay in an RC circuit). Options B and D are incorrect because, while related, the time constant for an *RL circuit* is fundamentally defined in terms of *current* change. The equivalent definition for an RC circuit typically refers to capacitor voltage.
Related Questions
3-14B2 What is the meaning of the term “time constant of an RC circuit”? The time required to charge the capacitor in the circuit to:3-14B3 What is the term for the time required for the current in an RL circuit to build up to 63.2% of the maximum value?3-14B5 After two time constants, the capacitor in an RC circuit is charged to what percentage of the supply voltage?3-14B6 After two time constants, the capacitor in an RC circuit is discharged to what percentage of the starting voltage?3-15B1 What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors all in parallel?