Find Time Constant for RC Circuit: Solve the Equation!

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Homework Help Overview

The discussion revolves around determining the time constant for an RC circuit involving a capacitor and resistors. Participants are examining the implications of the circuit configuration when a switch is closed.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate the time constant using the formula τ = R_eq C, questioning the outcome of their calculation. Other participants discuss the configuration of the circuit when the switch is closed, specifically addressing the behavior of components in parallel and the implications for voltage across the capacitor.

Discussion Status

Participants are exploring the relationship between the circuit components and the resulting time constant. Some have suggested that the time constant may be zero based on the ideal conditions of the voltage source and negligible resistance in the wires. There is an ongoing examination of the assumptions made regarding the circuit setup.

Contextual Notes

There is a mention of an attached diagram that may provide additional context, but its contents are not described in the discussion. The original poster's calculation appears to conflict with the expected outcome, prompting further inquiry into the assumptions about the circuit configuration.

utkarshakash
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Homework Statement


The time constant of charging for the capacitor shown in the figure is


Homework Equations



See attached diagram

The Attempt at a Solution



\tau = R_{eq} C

R_{eq} = R/2

So the answer should be t= RC/2. But the correct answer is 0! :confused:
 

Attachments

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Once the switch is closed all the components are in parallel, right? What's the rule for the potential across components in parallel?
 
gneill said:
Once the switch is closed all the components are in parallel, right? What's the rule for the potential across components in parallel?

They all have the same potential difference.
 
utkarshakash said:
They all have the same potential difference.

Right. And if the voltage source is ideal and the wires have entirely negligible resistance, then the capacitor voltage immediately after the switch closes must be...
 
gneill said:
Right. And if the voltage source is ideal and the wires have entirely negligible resistance, then the capacitor voltage immediately after the switch closes must be...

It should be V. Thus time constant must be 0. Thanks !
 

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