Finding the Time Constant in a circuit

In summary, the time constant in the given circuit can be found using the equation T = RC, where R is the equivalent resistance and C is the capacitance. However, when the capacitor is discharging, the resistors may not be in series or parallel, making it difficult to find the equivalent resistance. The diagram may not be accurate as the wire connecting the switch and R1 may prevent the switch and voltage source from affecting the rest of the circuit.
  • #1
mlb2358
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Homework Statement


Find the time constant in the following circuit when switch K1 is open.
circuit_zps5c940856.jpg

R1 = 100 Ohms
R2 = 200 Ohms
C1 = 6 micro Farads
E1 = 9V

Homework Equations



T = RC

The Attempt at a Solution


When the resistors are in series or parallel, I am clear on how to do this, however when the capacitor is discharging, I don't think the resistors are in series or parallel, so I don't know how to find the equivalent resistance.
 
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  • #2
Is the diagram correct? What is that wire that runs from where the switch and R1 meet down to the bottom node? Doesn't it prevent the switch and voltage source from affecting the rest of the circuit?
 

1. What is the time constant in a circuit?

The time constant in a circuit is a measure of how quickly the voltage or current in the circuit changes in response to a sudden change in input.

2. How can I find the time constant in a circuit?

The time constant can be found by dividing the resistance (in ohms) by the capacitance (in farads) in the circuit.

3. Why is it important to know the time constant in a circuit?

Knowing the time constant allows us to predict the behavior of the circuit and how quickly it will reach a steady state after a sudden change in input.

4. What are the units of the time constant?

The units of the time constant are seconds (s) since it is calculated by dividing resistance (ohms) by capacitance (farads), which are both measured in standard metric units.

5. Can the time constant change in a circuit?

Yes, the time constant can change if the resistance or capacitance in the circuit changes. It is also affected by the type of circuit and the components used.

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