Electronic Technology Fundamentals Exam Questions | Generated by AI
Sample Exam Questions: Fundamentals of Electronic Technology (III)
(Based on Wen Xidong Edition, National Higher Education Self-Study Examination)
This set draws from past 自考 papers for the course 电子技术基础（三）. Topics include AC circuit analysis, semiconductors, transistors, and operational amplifiers. Questions are in English (translated from Chinese originals) for clarity. Each single-choice question is worth 1 point; the analysis question is worth 5 points.
Section I: Single-Choice Questions
Select the correct option (A, B, C, or D) for each.
-
Among the following descriptions of the characteristics of an ideal voltage source, the correct one is:
A. The internal resistance of the ideal voltage source signal source tends to infinity.
B. Ideal voltage sources can be connected in parallel at any time.
C. The output voltage of the ideal voltage source is related to the load.
D. The current flowing through the ideal voltage source is related to the load. -
Given the phasor current flowing through the inductive reactance \( \omega L = 2 \, \Omega \) is \( I = 10 \angle 30^\circ \) mA, then the phasor voltage across it is:
A. \( U = 20 \angle 0^\circ \) mV
B. \( U = 20 \angle 120^\circ \) mV
C. \( U = 20 \angle 30^\circ \) mV
D. \( U = 20 \angle -60^\circ \) mV -
Assume capacitor \( C = 1 \, \mu \mathrm{F} \), the voltage across the capacitor is \( \cos(100 \pi t) \) mV, then the current flowing through the capacitor is:
A. \( i_c(t) = -0.1 \times 10^{-6} \pi \sin(100 \pi t) \) A
B. \( i_c(t) = 0.1 \times 10^{-6} \pi \sin(100 \pi t) \) A
C. \( i_c(t) = -0.1 \times 10^{-6} \sin(100 \pi t) \) A
D. \( i_c(t) = 0.1 \times 10^{-6} \sin(100 \pi t) \) A -
The majority carrier in P-type semiconductor is:
A. Free electrons
B. Holes
C. Trivalent impurity atoms
D. Trivalent impurity ions -
Given the potentials of the three electrodes of a certain crystal triode as shown in the figure (emitter-base-collector voltages indicating NPN silicon transistor characteristics), the type of this transistor is:
(Figure description: Emitter at 0V, base at 0.7V, collector at 5V – typical forward-biased NPN silicon junction.)
A. PNP type germanium tube
B. NPN type germanium tube
C. PNP type silicon tube
D. NPN type silicon tube
Section II: Analysis Question
Question 31 (5 points): In the circuit shown in Figure 31 (a basic inverting op-amp configuration with input resistor \( R_i = 10 \, \mathrm{k} \Omega \), feedback resistor \( R_f = 20 \, \mathrm{k} \Omega \), input voltage \( U_i = 10 \) V), calculate the output voltage \( U_o \).
(Figure description: Standard op-amp inverting amplifier; non-inverting input grounded. Use the gain formula: \( U_o = - \frac{R_f}{R_i} \times U_i \).)
Solution Hint: Apply the virtual ground principle (inverting input at 0V potential). The voltage drop across \( R_i \) equals \( U_i \), so current \( I = \frac{U_i}{R_i} \). Then \( U_o = -I \times R_f \). Expected result: \( U_o = -20 \) V.
These align with chapters like AC phasors (Ch. 2), semiconductors (Ch. 3–4), and op-amps (Ch. 5). Practice tip: Review phasor arithmetic, carrier transport, and ideal op-amp rules.
References: