Current Electricity and Circuits

Question 1

Multiple choice

For the circuit shown in the figure, the Thevenin voltage and resistance looking into X - Y are

^{$\dfrac{4}{3}$}V, 2^$\Omega$
4V, ^{$\dfrac{2}{3}$}^$\Omega$
^{$\dfrac{4}{3}$}V, ^{$\dfrac{2}{3}$}^$\Omega$

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Answer

4V, 2^$\Omega$

Question 2

Multiple choice

The equivalent inductance measured between the terminals 1 and 2 for the circuit shown in the figure is

L₁+ L₂+ M
L₁+ L₂ – M
L₁+ L₂ + 2M

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Answer

L₁+ L₂ – 2M

Question 3

Multiple choice

How much current will flow in a 100 Hz series RLC circuit, if V_S = 20 V, R_T= 66 ohms and X_T= 47 ohms?

1.05 A
303 mA
247 mA
107 mA

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Answer

(0.18 + j0.72)

Answer

1 $\Omega$resistance in series with 1 F capacitor

Answer

6.4 - j4.8

Answer

$\dfrac{s+2}{s^2+s+1}$

Answer

|R_neg| $\le$ Re Z₁ (j$\omega$), $\forall \omega$

Answer

i(t)=0.5-0.125e-¹⁰⁰⁰tA

Answer

$\dfrac{10\sqrt 3}{2} \angle 90^\circ Amps$

Answer

2$\dfrac{d^2i}{dt^2} + 2 \dfrac{di}{dt} + i(t) = cos t$

Answer

$\left[ \begin{array} \ R+Ls+\dfrac{1}{Cs} & -Ls \\\\ -Ls & R+Ls+\dfrac{1}{Cs} \end{array} \right] \left[ \begin{array} \ I_1 & (s) \\\\ I_2 & (s) \end{array} \right] = \left[ \begin{array} -\dfrac{V}{S} \\\\ 0 \end{array} \right] $

Question 4

Multiple choice

The current flowing through the resistance R in the circuit in figure has the form P cos 4t, where P is

(0.46 + j1.90)
-(0.18 + j1.90)
-(0.192 + j0.144)

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Question 5

Multiple choice

In the circuit shown below, the current I is equal to

14 0؛A
2.0 0ºA
2.8 0ºA
3.2 0ºA

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Question 6

Multiple choice

A source of angular frequency 1 rad/sec has a source impedance consisting of 1 $\Omega$resistance in series with 1 H inductance. The load that will obtain the maximum power transfer is

1 $\Omega$resistance
1 $\Omega$resistance in parallel with 1 H inductance
1 $\Omega$ resistance in parallel with 1 F capacitor

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Question 7

Multiple choice

For the R – L circuit shown in the figure, the input voltage v_i(t) = u(t). The current i(t) is

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Question 8

Multiple choice

In the circuit shown below, the Norton equivalent current in amperes with respect to the terminals P and Q is

6.56 - j7.87
10 + j0
16 + j0 

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Question 9

Multiple choice

The circuit shown in the figure has initial current i_L (0^-) = 1 A through the inductor and an initial voltage v_C(0^-) = -1 V across the capacitor. For input = v(t) = u (t), the Laplace transform of the current i(t) for t $\ge$0 is

$\dfrac{s}{s^2+s+1}$
$\dfrac{s-2}{s^2+s+1}$
$\dfrac{1}{s^2+s+1}$

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Question 10

Multiple choice

A negative resistance R_neg is connected to a passive network N having driving point impedance Z₂(s) as shown below. For Z₁(s) to be positive real,

|R_neg| $\le$ | Z₁ (j$\omega$), $\forall \omega$
|R_neg| $\le$ | ImZ₁ (j$\omega$), $\forall \omega$
|R_neg| $\le$ $\angle$ Z₁ (j$\omega$), $\forall \omega$

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Question 11

Multiple choice

A 2 mH inductor with some initial current can be represented as shown below, where s is the Laplace Transform Variable. The value of initial current is

0.5 A
2.0 A
1.0 A
0.0 A

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Question 12

Multiple choice

In the circuit shown, the switch S is open for a long time and is closed at t = 0. The current i(t) for t$\ge$ 0⁺ is

i(t)=1.5-0.125e^-1000tA
i(t)=0.5-0.5e^-1000tA
i(t)=0.375e^-1000tA

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Question 13

Multiple choice

For the circuit in the figure, the instantaneous current i₁ (t) is

$\dfrac{10\sqrt 3}{2} \angle -90^\circ Amps$
$5 \angle 60^\circ Amps$
$5 \angle -60^\circ Amps$

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Question 14

Multiple choice

The differential equation for the current i(t) in the circuit of figure given below is

2$\dfrac{d^2i}{dt^2} + 2 \dfrac{di}{dt} + i(t) = sin t$
$\dfrac{d^2i}{dt^2} + 2 \dfrac{di}{dt} + 2i(t) = cos t$
$\dfrac{d^2i}{dt^2} + 2 \dfrac{di}{dt} + 2i(t) = sin t$

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Question 15

Multiple choice

Assume that the switch S is in position 1 for a long time and thrown to position 2 at t = 0.

I₁ (s) and I₂ (s) are the Laplace transforms of i₁ (t) and i₂ (t) respectively. The equation for the loop current I₁ (s) and I₂ (s) for the circuit shown in figure Q.33-34, after the switch is brought from position 1 to position 2 at t = 0, are

$\left[ \begin{array} \ R+Ls+\dfrac{1}{Cs} & -Ls \\\\ -Ls & R+\dfrac{1}{Cs} \end{array} \right] \left[ \begin{array} \ I_1 & (s) \\\\ I_2 & (s) \end{array} \right] = \left[ \begin{array} \ -\dfrac{V}{S} \\\\ 0 \end{array} \right] $
$\left[ \begin{array} \ R+Ls+\dfrac{1}{Cs} & -Ls \\\\ -Ls & R+Ls+\dfrac{1}{Cs} \end{array} \right] \left[ \begin{array} \ I_1 & (s) \\\\ I_2 & (s) \end{array} \right] = \left[ \begin{array} \ \dfrac{V}{S} \\\\ 0 \end{array} \right] $
$\left[ \begin{array} \ R+Ls+\dfrac{1}{Cs} & -Ls \\\\ -Ls & R+Ls+\dfrac{1}{Cs} \end{array} \right] \left[ \begin{array} \ I_1 & (s) \\\\ I_2 & (s) \end{array} \right] = \left[ \begin{array} \ -\dfrac{V}{S} \\\\ 0 \end{array} \right] $

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Current Electricity and Circuits

Current Electricity and Circuits Questions