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ELEC 273 LABS 1–4 COMPREHENSIVE EXAM PREP:
PRACTICE QUESTIONS WITH ANSWERS AND DETAILED
RATIONALES – COMPLETE STUDY GUIDE, LATEST 2026
EDITION
This complete practice examination is designed for students preparing for ELEC 273 laboratory
assessments covering Labs 1 through 4. It provides 150 advanced, exam-style multiple-choice
questions on fundamental electrical measurements, resistor color codes, breadboard
construction, Ohm’s law, series and parallel circuits, Kirchhoff’s voltage and current laws,
voltage and current dividers, Thevenin and Norton equivalent circuits, superposition,
oscilloscope operation, function generator use, and basic AC measurements. Each question
includes a detailed rationale explaining the correct answer and why alternatives are less
suitable. The 2026 edition aligns with standard introductory electrical engineering laboratory
curricula. Use this comprehensive review package to assess readiness, identify knowledge gaps,
and strengthen practical competencies for your lab exams. Perfect for students seeking mastery
in circuit analysis and laboratory techniques.
Table of Contents
1. Laboratory Safety and Equipment Fundamentals
2. Resistor Color Code and Basic Measurements
3. Ohm’s Law and Series Circuits
4. Parallel Circuits and Kirchhoff’s Current Law
5. Kirchhoff’s Voltage Law and Loop Analysis
6. Voltage and Current Dividers
7. Thevenin and Norton Equivalent Circuits
8. Superposition and Source Transformation
9. Oscilloscope and Function Generator Operation
10. AC Measurements and Phase Relationships
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1: Which of the following is the primary purpose of a breadboard in an electronics laboratory?
A) To provide a permanent soldered connection for circuit components
B) To allow rapid prototyping and temporary connection of circuit components without soldering
C) To measure electrical resistance automatically
D) To generate high-voltage signals
Correct Answer: B
A breadboard enables quick assembly and modification of circuits using spring clip terminals,
eliminating the need for soldering. It is not for permanent connections, resistance measurement,
or signal generation.
2: The primary safety rule when working with energized circuits in a laboratory is to:
A) Use only one hand when probing live circuits
B) Wear insulating gloves at all times
C) Keep the circuit energized while making connections
D) Use metal tools to touch both terminals simultaneously
Correct Answer: A
Using one hand reduces the risk of current passing through the chest, minimizing electric shock
hazards. Gloves are good but not always required; connections should be made with power off;
metal tools touching both terminals can cause short circuits.
3: A digital multimeter (DMM) is set to measure resistance. Before connecting the probes to a
resistor, you should:
A) Connect the circuit to a power source
B) Ensure the resistor is isolated from any power source
C) Short the probes together and adjust the display to zero
D) Set the DMM to AC voltage
Correct Answer: B
Measuring resistance requires the component to be unpowered to avoid damaging the meter and
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obtaining incorrect readings. Power must be off; zeroing is for analog meters; setting to AC
voltage is wrong.
4: The color code on a resistor reads brown-black-red-gold. What is its nominal resistance and
tolerance?
A) 100 Ω, ±5%
B) 1 kΩ, ±5%
C) 10 Ω, ±10%
D) 1 kΩ, ±10%
Correct Answer: B
Brown=1, black=0, red=2 zeros → 1000 Ω = 1 kΩ; gold=±5%. Option A uses red as multiplier
incorrectly? Actually brown-black-red = 1 0 × 10² = 1000 Ω. So B is correct.
5: A resistor has color bands orange-orange-brown-silver. Its resistance is:
A) 330 Ω, ±10%
B) 33 Ω, ±5%
C) 330 Ω, ±5%
D) 3.3 kΩ, ±10%
Correct Answer: A
Orange=3, orange=3, brown=×10¹ → 33×10 = 330 Ω; silver=±10%. Option C uses gold
tolerance; B wrong multiplier; D wrong value.
6: When measuring current in a circuit, the ammeter must be connected:
A) In parallel with the component
B) In series with the component
C) Across the voltage source
D) Across a resistor
Correct Answer: B
An ammeter must be placed in series so that all current flows through it. Connecting in parallel
would create a short circuit and potentially blow the meter fuse.
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7: The input resistance of an ideal voltmeter is:
A) Zero
B) Infinite
C) Equal to the circuit resistance
D) 1 kΩ
Correct Answer: B
An ideal voltmeter draws no current, so its input resistance is infinite, avoiding loading effects.
Real voltmeters have high but finite resistance.
8: A DMM is set to the 20 V DC range. The display reads “OL.” This indicates:
A) The voltage is exactly 20 V
B) The measured voltage exceeds the selected range
C) The circuit is open
D) The meter is defective
Correct Answer: B
“OL” means overload—the input exceeds the selected range. Select a higher voltage range to
obtain a reading.
9: The tolerance band on a resistor is absent. This means the tolerance is:
A) ±1%
B) ±5%
C) ±20%
D) ±10%
Correct Answer: C
If no tolerance band is present, the resistor is assumed to have a ±20% tolerance (old standard).
Common four-band resistors use gold or silver for tolerance.
10: When measuring resistance with a DMM, the leads have a residual resistance of 0.5 Ω. For
accurate low-resistance measurements, you should:
A) Ignore the lead resistance
B) Subtract the lead resistance from the reading
ELEC 273 LABS 1–4 COMPREHENSIVE EXAM PREP:
PRACTICE QUESTIONS WITH ANSWERS AND DETAILED
RATIONALES – COMPLETE STUDY GUIDE, LATEST 2026
EDITION
This complete practice examination is designed for students preparing for ELEC 273 laboratory
assessments covering Labs 1 through 4. It provides 150 advanced, exam-style multiple-choice
questions on fundamental electrical measurements, resistor color codes, breadboard
construction, Ohm’s law, series and parallel circuits, Kirchhoff’s voltage and current laws,
voltage and current dividers, Thevenin and Norton equivalent circuits, superposition,
oscilloscope operation, function generator use, and basic AC measurements. Each question
includes a detailed rationale explaining the correct answer and why alternatives are less
suitable. The 2026 edition aligns with standard introductory electrical engineering laboratory
curricula. Use this comprehensive review package to assess readiness, identify knowledge gaps,
and strengthen practical competencies for your lab exams. Perfect for students seeking mastery
in circuit analysis and laboratory techniques.
Table of Contents
1. Laboratory Safety and Equipment Fundamentals
2. Resistor Color Code and Basic Measurements
3. Ohm’s Law and Series Circuits
4. Parallel Circuits and Kirchhoff’s Current Law
5. Kirchhoff’s Voltage Law and Loop Analysis
6. Voltage and Current Dividers
7. Thevenin and Norton Equivalent Circuits
8. Superposition and Source Transformation
9. Oscilloscope and Function Generator Operation
10. AC Measurements and Phase Relationships
,2|Page
1: Which of the following is the primary purpose of a breadboard in an electronics laboratory?
A) To provide a permanent soldered connection for circuit components
B) To allow rapid prototyping and temporary connection of circuit components without soldering
C) To measure electrical resistance automatically
D) To generate high-voltage signals
Correct Answer: B
A breadboard enables quick assembly and modification of circuits using spring clip terminals,
eliminating the need for soldering. It is not for permanent connections, resistance measurement,
or signal generation.
2: The primary safety rule when working with energized circuits in a laboratory is to:
A) Use only one hand when probing live circuits
B) Wear insulating gloves at all times
C) Keep the circuit energized while making connections
D) Use metal tools to touch both terminals simultaneously
Correct Answer: A
Using one hand reduces the risk of current passing through the chest, minimizing electric shock
hazards. Gloves are good but not always required; connections should be made with power off;
metal tools touching both terminals can cause short circuits.
3: A digital multimeter (DMM) is set to measure resistance. Before connecting the probes to a
resistor, you should:
A) Connect the circuit to a power source
B) Ensure the resistor is isolated from any power source
C) Short the probes together and adjust the display to zero
D) Set the DMM to AC voltage
Correct Answer: B
Measuring resistance requires the component to be unpowered to avoid damaging the meter and
,3|Page
obtaining incorrect readings. Power must be off; zeroing is for analog meters; setting to AC
voltage is wrong.
4: The color code on a resistor reads brown-black-red-gold. What is its nominal resistance and
tolerance?
A) 100 Ω, ±5%
B) 1 kΩ, ±5%
C) 10 Ω, ±10%
D) 1 kΩ, ±10%
Correct Answer: B
Brown=1, black=0, red=2 zeros → 1000 Ω = 1 kΩ; gold=±5%. Option A uses red as multiplier
incorrectly? Actually brown-black-red = 1 0 × 10² = 1000 Ω. So B is correct.
5: A resistor has color bands orange-orange-brown-silver. Its resistance is:
A) 330 Ω, ±10%
B) 33 Ω, ±5%
C) 330 Ω, ±5%
D) 3.3 kΩ, ±10%
Correct Answer: A
Orange=3, orange=3, brown=×10¹ → 33×10 = 330 Ω; silver=±10%. Option C uses gold
tolerance; B wrong multiplier; D wrong value.
6: When measuring current in a circuit, the ammeter must be connected:
A) In parallel with the component
B) In series with the component
C) Across the voltage source
D) Across a resistor
Correct Answer: B
An ammeter must be placed in series so that all current flows through it. Connecting in parallel
would create a short circuit and potentially blow the meter fuse.
, 4|Page
7: The input resistance of an ideal voltmeter is:
A) Zero
B) Infinite
C) Equal to the circuit resistance
D) 1 kΩ
Correct Answer: B
An ideal voltmeter draws no current, so its input resistance is infinite, avoiding loading effects.
Real voltmeters have high but finite resistance.
8: A DMM is set to the 20 V DC range. The display reads “OL.” This indicates:
A) The voltage is exactly 20 V
B) The measured voltage exceeds the selected range
C) The circuit is open
D) The meter is defective
Correct Answer: B
“OL” means overload—the input exceeds the selected range. Select a higher voltage range to
obtain a reading.
9: The tolerance band on a resistor is absent. This means the tolerance is:
A) ±1%
B) ±5%
C) ±20%
D) ±10%
Correct Answer: C
If no tolerance band is present, the resistor is assumed to have a ±20% tolerance (old standard).
Common four-band resistors use gold or silver for tolerance.
10: When measuring resistance with a DMM, the leads have a residual resistance of 0.5 Ω. For
accurate low-resistance measurements, you should:
A) Ignore the lead resistance
B) Subtract the lead resistance from the reading
