Subelement B: Electrical Math— Topic 14: RC Time Constants-1
Question 3-14B5
Element 3 (GROL)After two time constants, the capacitor in an RC circuit is charged to what percentage of the supply voltage?
Explanation
The time constant (τ) in an RC circuit is a critical value determined by multiplying the resistance (R) by the capacitance (C). It represents the time it takes for a capacitor to charge or discharge a specific amount exponentially.
When charging, the capacitor voltage increases over time:
* After one time constant (1τ), the capacitor charges to approximately 63.2% of the supply voltage.
* After two time constants (2τ), it charges further to approximately 86.5% of the supply voltage.
* After three time constants (3τ), it reaches about 95% of the supply voltage.
* By five time constants (5τ), it's considered fully charged (over 99%).
Therefore, after two time constants, the capacitor is charged to 86.5% of the supply voltage.
* A) 36.8% represents the remaining voltage after one time constant of discharge, not charge.
* B) 63.2% is the charge after one time constant.
* D) 95% is the charge after three time constants.
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