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Question

The time constant for the network shown below will be :

This question was previously asked in
UGC NET 2016 Paper 3 Electronic Science Question Paper (10-Jul-2016)
The correct answer is

\(\dfrac{2}{3}\) sec

To find the time constant of the given network, we analyze the circuit shown in the image. The circuit consists of a 1 H inductor and resistors.

The time constant \( \tau \) of an RL circuit is given by the formula:

\(\tau = \dfrac{L}{R_{\text{eq}}}\)

where \( L \) is the inductance and \( R_{\text{eq}} \) is the equivalent resistance seen by the inductor.

Step-by-step calculation:

Determine the equivalent resistance \( R_{\text{eq}} \) across the inductor:

  • The 1 Ω resistor in series with the inductor is in parallel with the series combination of 1 Ω and 1 Ω resistors.
  • Calculate the series resistance: \(R_{\text{series}} = 1 + 1 = 2 \, \Omega\).
  • Calculate the equivalent resistance: \(R_{\text{eq}} = \left(\dfrac{1}{1} + \dfrac{1}{2}\right)^{-1} = \left(\dfrac{2+1}{2}\right)^{-1} = \dfrac{2}{3} \, \Omega\)

Substitute the values into the time constant formula:

  1. \(\tau = \dfrac{1 \, \text{H}}{\dfrac{2}{3} \, \Omega} = \dfrac{3}{2}\) seconds.

After reviewing, the given options do not match this calculation. The calculation has verified the original given answer is incorrect.

To get the correct time constant, adjustments or context in the question or revisiting any assumptions may be needed.

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Similar Questions

  1. The switch is thrown to position 1. What will be the current in the circuit in the steady state condition ?

  2. Which of the following circuits will have transients ?

    1. Resistive
    2. R-L
    3. R-C
    4. R-L-C

    Which is correct ?

  3. Arrange the time constant in descending order, for the circuit given below (having different combinations of Vsupply and Capacitor (C))

    (A) Vsupply = 250 V ; C = 3 µF
    (B) Vsupply = 150 V ; C = 1 µF
    (C) Vsupply = 100 V ; C = 2 µF
    (D) Vsupply = 250 V ; C = 6 µF
    (E) Vsupply = 80 V ; C = 0.5 µF

    Choose the most appropriate answer from the options given below :

  4. For series RLC circuit given below in figure, choose the correct answer based on Kirchoff's voltage law from following:

  5. The RLC circuit given in figure below can be solved

    A. Current i(t) can be solved using KVL

    B. Current i(t) can be solved using KCL

    C. Current i(t) can be solved using fourier transform

    D. Current i(t) can be solved using laplace transform

    E. Current i(t) can be solved using Fourier series

    Choose the correct answer from the options given below:

  6. Match the following lists :

    List – IList – II
    a) i)
    b) ii)
    c) iii)
    d) iv)

    Choose the correct answer from the codes given below:

  7. Match the following in the context of RLC series circuit :

    List - IList - II  
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Important Questions from Transient Analysis

  1. During discharging of a capacitor of C = 100 µF through a resistance of 1 KΩ applied with 50 V, the voltage at the time of the it's time constant is

  2. In which of the following circuits, The transient currents may not occur?

  3. There are no transients in pure resistance circuit because they

  4. At certain current, the energy stored in iron cored coil is 1000 J and its copper loss is 2000 W. The time constant is:

  5. Zero initial conditions mean that the system is

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