Elevator Mechanic Practice Exam

What does a 1 time constant represent in a circuit with capacitance?

1. 56.8%

2. 99%

3. 50%

4. 63.2%

The correct answer is: 63.2%

The correct answer is indeed 63.2%. In a circuit with capacitance, the time constant is a crucial measure that defines how quickly the capacitor charges or discharges through a resistor. The time constant, often denoted by the Greek letter tau (τ), is calculated by multiplying the resistance (R) in ohms by the capacitance (C) in farads. When a capacitor initially begins to charge, the voltage across the capacitor increases exponentially. After one time constant has elapsed, the capacitor will have reached approximately 63.2% of its maximum charge voltage. This value is derived from the mathematical formula describing the charging process, which shows that after one time constant, the capacitor accumulates roughly 63.2% of the total voltage that it will eventually reach. This concept is fundamental in electronics, especially in applications involving RC (resistor-capacitor) circuits, as it impacts how quickly signals can change and how circuits respond to voltage changes over time.