Subelement B: Electrical Math— Topic 15: RC Time Constants-2
Question 3-15B4
Element 3 (GROL)What is the time constant of a circuit having a 220-microfarad capacitor and a 1-megohm resistor in parallel?
Explanation
The time constant (τ) of a resistor-capacitor (RC) circuit, such as one with a resistor and capacitor in parallel or series, is a fundamental concept in radio theory. It represents the time required for the capacitor to charge to approximately 63.2% of the applied voltage or discharge to 36.8% of its initial voltage.
The formula for the time constant is τ = R * C, where R is resistance in ohms and C is capacitance in farads.
Given:
* Resistance (R) = 1 megohm (1 MΩ) = 1,000,000 ohms
* Capacitance (C) = 220 microfarads (220 µF) = 0.000220 farads
Plugging these values into the formula:
τ = 1,000,000 Ω * 0.000220 F
τ = 220 seconds
Thus, the time constant is 220 seconds. Options B, C, and D are incorrect because they result from miscalculations or incorrect unit conversions, such as forgetting to convert megohms to ohms or microfarads to farads.
Related Questions
3-15B2 What is the time constant of a circuit having two 100-microfarad capacitors and two 470-kilohm resistors all in series?3-15B3 What is the time constant of a circuit having a 100-microfarad capacitor and a 470-kilohm resistor in series?3-15B5 What is the time constant of a circuit having two 100-microfarad capacitors and two 470-kilohm resistors all in parallel?3-15B6 What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors all in series?3-16B1 What is the impedance of a network composed of a 0.1-microhenry inductor in series with a 20-ohm resistor, at 30 MHz? Specify your answer in rectangular coordinates.