Subelement B: Electrical Math— Topic 14: RC Time Constants-1
Question 3-14B2
Element 3 (GROL)What is the meaning of the term “time constant of an RC circuit”? The time required to charge the capacitor in the circuit to:
Explanation
The time constant ($\tau$) of an RC (resistor-capacitor) circuit is a crucial parameter indicating how quickly a capacitor charges or discharges through a resistor. It is calculated by multiplying the resistance (R) in ohms by the capacitance (C) in farads, resulting in a time in seconds.
When a capacitor in an RC circuit is charging from a DC supply, one time constant represents the time it takes for the voltage across the capacitor to reach approximately 63.2% of the final applied supply voltage. This value is derived from the exponential charging curve, specifically (1 - 1/e), where 'e' is Euler's number. Conversely, when discharging, it takes one time constant for the capacitor's voltage to fall to 36.8% of its initial voltage. Therefore, option D correctly describes the charging scenario. RC circuits are fundamental in amateur radio for filtering, timing circuits, and waveform shaping.
Related Questions
3-13B6 What does the power factor equal in an R-L circuit having a 30 degree phase angle between the voltage and the current?3-14B1 What is the term for the time required for the capacitor in an RC circuit to be charged to 63.2% of the supply voltage?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?3-14B4 What is the meaning of the term “time constant of an RL circuit”? The time required for the:3-14B5 After two time constants, the capacitor in an RC circuit is charged to what percentage of the supply voltage?