The current in the RL circuit shown below reaches half its maximum value in 1.75 ms after the switch S1 is thrown. Determine (a) the time constant of the circuit and (b) the resistance of the circuit if ?=250mH.

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57) The current in the RL circuit shown below reaches half its maximum value in 1.75 ms after the switch S1 is thrown. Determine (a) the time constant of the circuit and (b) the resistance of the circuit if ?=250mH.

### Transcription and Explanation of RL Circuit Analysis

#### Given:
- Equation: \( I(t = 1.75 \times 10^{-3}s) = \frac{I_{\text{max}}}{2} \)
- Inductance: \( L = 250 \times 10^{-3} \, \text{H} \)

#### Questions:
- a) Find \(\tau_{\text{RL}}\).
- b) Determine \(R\).

#### Circuit Diagram:
The circuit consists of a resistor (\(R\)) and an inductor (\(L\)) in series with a voltage source (\(\mathcal{E}\)).

#### Solution Steps:

1. **Time Constant \(\tau_{\text{RL}}\):**

   The time constant for an RL circuit is given by:
   \[
   \tau_{\text{RL}} = \frac{L}{R}
   \]

2. **Current Equation:**
   
   \[
   I(t) = I_{\text{max}} \left(1 - e^{-\frac{R}{L}t} \right)
   \]

   Rearranging for \(\frac{I(t)}{I_{\text{max}}}\):
   \[
   \frac{I(t)}{I_{\text{max}}} = 1 - e^{-\frac{t}{\tau_{\text{RL}}}}
   \]

   Solving for \(e^{-\frac{t}{\tau_{\text{RL}}}}\):
   \[
   1 - \frac{I(t)}{I_{\text{max}}} = e^{-\frac{t}{\tau_{\text{RL}}}}
   \]

3. **Taking the Natural Logarithm:**

   \[
   \ln \left(1 - \frac{I(t)}{I_{\text{max}}}\right) = -\frac{t}{\tau_{\text{RL}}}
   \]

   Rearrange to find \(\tau_{\text{RL}}\):
   \[
   \tau_{\text{RL}} = \frac{-t}{\ln \left(1 - \frac{I(t)}{I_{\text{max}}}\right)}
   \]

   Substitute \(t = 1.75 \times 10^{-3}\) and \(\frac{I(t)}{I_{\text{max}}
Transcribed Image Text:### Transcription and Explanation of RL Circuit Analysis #### Given: - Equation: \( I(t = 1.75 \times 10^{-3}s) = \frac{I_{\text{max}}}{2} \) - Inductance: \( L = 250 \times 10^{-3} \, \text{H} \) #### Questions: - a) Find \(\tau_{\text{RL}}\). - b) Determine \(R\). #### Circuit Diagram: The circuit consists of a resistor (\(R\)) and an inductor (\(L\)) in series with a voltage source (\(\mathcal{E}\)). #### Solution Steps: 1. **Time Constant \(\tau_{\text{RL}}\):** The time constant for an RL circuit is given by: \[ \tau_{\text{RL}} = \frac{L}{R} \] 2. **Current Equation:** \[ I(t) = I_{\text{max}} \left(1 - e^{-\frac{R}{L}t} \right) \] Rearranging for \(\frac{I(t)}{I_{\text{max}}}\): \[ \frac{I(t)}{I_{\text{max}}} = 1 - e^{-\frac{t}{\tau_{\text{RL}}}} \] Solving for \(e^{-\frac{t}{\tau_{\text{RL}}}}\): \[ 1 - \frac{I(t)}{I_{\text{max}}} = e^{-\frac{t}{\tau_{\text{RL}}}} \] 3. **Taking the Natural Logarithm:** \[ \ln \left(1 - \frac{I(t)}{I_{\text{max}}}\right) = -\frac{t}{\tau_{\text{RL}}} \] Rearrange to find \(\tau_{\text{RL}}\): \[ \tau_{\text{RL}} = \frac{-t}{\ln \left(1 - \frac{I(t)}{I_{\text{max}}}\right)} \] Substitute \(t = 1.75 \times 10^{-3}\) and \(\frac{I(t)}{I_{\text{max}}
The image depicts an electrical circuit diagram featuring an inductor (L), a resistor (R), a switch (S1), and a battery (denoted by
Transcribed Image Text:The image depicts an electrical circuit diagram featuring an inductor (L), a resistor (R), a switch (S1), and a battery (denoted by
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