Physics

Current Electricity and Circuits

450 Questions

Current electricity and circuits questions cover resistors, EMF, internal resistance, and power calculations in series and parallel configurations. Solving these builds a strong understanding of electrical principles and circuit analysis. These physics problems are highly relevant for technical and science aptitude tests.

Resistor combinationsPower dissipationEMF and internal resistanceAC circuit analysisOperational amplifiers

Current Electricity and Circuits Questions

Multiple choice

The circuit using a BJT with $\beta$ = 50 and V_BE = 0.7 V is shown in figure. The base current I_B and collector voltage V_C are respectively

$43 \mu A\hspace{0.2cm} and \hspace{0.2cm}11.4 \hspace{0.1cm} volts$
$40 \mu A\hspace{0.2cm} and \hspace{0.2cm}16 \hspace{0.1cm} volts$
$45 \mu A\hspace{0.2cm} and \hspace{0.2cm}11 \hspace{0.1cm} volts$
$45 \mu A\hspace{0.2cm} and \hspace{0.2cm}10 \hspace{0.1cm} volts$

Reveal answer Fill a bubble to check yourself

Multiple choice

Given r_d = 20 k$\Omega$, I_DSS = 10 mA, V_p = -8 V.

I_D and I_DS under DC conditions are respectively

5.625 mA and 8.75 V
4.500 mA and 11.00 V
7.500 mA and 5.00 V
6.250 mA and 7.50 V

Reveal answer Fill a bubble to check yourself

Multiple choice

Given r_d = 20 k$\Omega$, I_DSS = 10 mA, V_p = -8 V.

Z_i and Z₀ of the circuit are respectively

2 M$\Omega$ and 2 k$\Omega$
$2 M \Omega \hspace{0.2cm} and \hspace{0.2cm} \frac{20}{11} k \Omega$
Infinity and 2 k$\Omega$
Infinity and $\frac{20}{11} k \Omega$

Reveal answer Fill a bubble to check yourself

Multiple choice

The input resistance R_i of the amplifier shown in the figure is

$\frac{30}{4} k \Omega$
10 k^$\Omega$
40 k^$\Omega$
infinite

Reveal answer Fill a bubble to check yourself

Multiple choice

A 30-Volts battery with zero source resistance is connected to a coaxial line of characteristic impedance of 50 Ohms at t = 0 second terminated in an unknown resistive load. The line length is that it takes 400 Js for an electromagnetic wave to travel from source end to load end and vice-versa. At t = 400ى s, the voltage at the load end is found to be 40 Volts.

The load resistance is

25 Ohms
50 Ohms
75 Ohms
100 Ohms

Reveal answer Fill a bubble to check yourself

Multiple choice

The steady-state current through the load resistance is

1.2 Amps
0.3 Amps
0.6 Amps
0.4 Amps

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Multiple choice

For the Zener diode shown in the figure, the Zener voltage at the knee is 7 V. The knee current is negligible and the Zener dynamic resistance is 10 ^$\Omega$. If the input voltage (V_i) ranges from 10 V to 16 V, what will be the range of out put voltage (V₀)?

7.00 V to 7.29 V
7.14 V to 7.29 V
7.14 V to 7.43 V
7.29 V to 7.43 V

Reveal answer Fill a bubble to check yourself

Multiple choice

In the Op-Amp circuit shown, assume that the diode current follows the equation I = I_s exp (V/V_T). For V_i = 2V, V₀ = V₀₁, and for V_i = 4 V, V₀ = V₀₂. The relationship between V₀₁ and V₀₂ is

V₀₂ = $\sqrt{2}$V₀₁
V₀₂ = e² V₀₁
V₀₂ = V₀₁ In 2
V₀₁ - V₀₂ = V_T In 2

Reveal answer Fill a bubble to check yourself

Multiple choice

In the circuit shown below, assume that the voltage drop across a forward biased diode is 0.7 V. The thermal voltage V_t = kT/q = 25 mV and small signal input v_i = V_p cos $(\omega t)$ where V_p = 100 mV.

The ac output voltage v_ac is

0.25cos ^{_{$(\omega t)$}} mV
1cos ^{_{$(\omega t)$}} mV
2cos ^{_{$(\omega t)$}}mV
22cos ^{_{$(\omega t)$}} mV

Reveal answer Fill a bubble to check yourself

Multiple choice

In the given circuit, the values of V₁ and V₂ respectively are

5 V and 25 V
10 V and 30 V
15 V and 35 V
0 V and 20 V

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Multiple choice

Consider the configuration shown in the figure which is a portion of a larger electrical network For R = 1^$\Omega$ and currents i1 = 2 A, i4 = - 1A, i5 = - 4 A, which one of the following is TRUE?

i₆ = 5 A
i₃ =- 4 A
Data is sufficient to conclude that the supposed currents are impossible
Data is insufficient to identify the currents i₂, i₃, and i₆

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Multiple choice

Consider the common emitter amplifier shown below with the following circuit parameters.

B = 100, g_m = 0.3861 A/V, r₀= ^_$\infty$, r_p = 259 W, R_S = 1k W, R_B = 93kW, R_C = 250 W, R_L = 1k W, C₁= ^_$\infty$and C₂ = 4.7mF.

The resistance seen by the source Vs is

258^$\Omega$
1252^$\Omega$
93 K^$\Omega$
$\infty$

Reveal answer Fill a bubble to check yourself

Multiple choice

Consider an impedance Z = R + jX marked with point P in an impedance Smith chart as shown in figure. The movement from point P along a constant resistance circle in the clockwise direction by an angle 45c is equivalent to