ELECTRICAL MECHANIC/TEST TECHNICIAN NEWEST EXAM
COMPLETE QUESTIONS AND CORRECT DETAILED ANSWERS
WITH RATIONALES | BRAND NEW VERSION!
SECTION 1: ELECTRICAL THEORY & FUNDAMENTALS (Questions 1–50)
Q1. What is the SI unit of electrical resistance?
A) Volt
B) Ampere
C) Ohm
D) Watt
Answer: C
Rationale: The ohm (Ω) is the SI unit of resistance. It is defined as the resistance
between two points when one volt produces one ampere.
Q2. Ohm's Law states that:
A) Power equals voltage times current
B) Voltage equals current times resistance
C) Current equals voltage times resistance
D) Resistance equals voltage times current
Answer: B
Rationale: V = I × R, the fundamental relationship in electrical circuits.
Q3. A circuit has 120 volts applied and draws 5 amperes. What is the resistance?
A) 24 Ω
B) 600 Ω
C) 0.0417 Ω
D) 125 Ω
Answer: A
Rationale: R = V / I = = 24 Ω.
Q4. The power dissipated in a resistor can be calculated using which formula?
A) P = I²R
1
,B) P = V²/R
C) P = VI
D) All of the above
Answer: D
Rationale: All three are equivalent forms derived from Ohm's Law.
Q5. A 100-watt light bulb is connected to a 120V source. What current does it
draw?
A) 0.833 A
B) 1.2 A
C) 8.33 A
D) 12 A
Answer: A
Rationale: I = P/V = 100/120 = 0.833 A.
Q6. What is the equivalent resistance of two 10 Ω resistors in series?
A) 5 Ω
B) 10 Ω
C) 20 Ω
D) 100 Ω
Answer: C
Rationale: Series resistances add: R_total = R1 + R2 = 10 + 10 = 20 Ω.
Q7. What is the equivalent resistance of two 10 Ω resistors in parallel?
A) 5 Ω
B) 10 Ω
C) 20 Ω
D) 100 Ω
Answer: A
Rationale: Parallel: 1/R_total = 1/10 + 1/10 = 2/10 => R_total = 5 Ω.
Q8. Kirchhoff's Voltage Law states that:
A) The sum of currents entering a node equals the sum of currents leaving
2
,B) The sum of voltages around a closed loop is zero
C) Power is conserved in a circuit
D) Voltage is directly proportional to current
Answer: B
Rationale: KVL: the algebraic sum of all voltages in a closed loop equals zero.
Q9. Kirchhoff's Current Law states that:
A) The sum of voltages around a closed loop is zero
B) The sum of currents entering a node equals the sum leaving
C) Current is inversely proportional to resistance
D) Power equals voltage times current
Answer: B
Rationale: KCL: charge conservation – at a node, total current in = total current
out.
Q10. What is the color code for a resistor with bands: Brown, Black, Red, Gold?
A) 100 Ω ±5%
B) 1,000 Ω ±5%
C) 10,000 Ω ±5%
D) 1,000 Ω ±10%
Answer: B
Rationale: Brown=1, Black=0, Red=multiplier ×100 => 10×100 = 1000 Ω,
Gold=±5%.
Q11. A resistor has a value of 4.7 kΩ with a tolerance of ±10%. What are the
minimum and maximum possible resistance values?
A) 4.23 kΩ to 5.17 kΩ
B) 4.0 kΩ to 5.4 kΩ
C) 4.23 Ω to 5.17 Ω
D) 4.7 kΩ exactly
Answer: A
Rationale: 10% of 4.7k = 0.47k; min = 4.7-0.47 = 4.23k; max = 4.7+0.47 = 5.17k.
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, Q12. Which of the following materials has the highest electrical conductivity?
A) Copper
B) Silver
C) Aluminum
D) Gold
Answer: B
Rationale: Silver has the highest conductivity of all metals, but copper is more
commonly used due to cost.
Q13. What is the temperature coefficient of resistance for most metals?
A) Positive
B) Negative
C) Zero
D) Infinite
Answer: A
Rationale: Metals have a positive temperature coefficient – resistance increases
with temperature.
Q14. A conductor's resistance is directly proportional to its:
A) Cross-sectional area
B) Length
C) Temperature
D) Both B and C
Answer: B
Rationale: R = ρ L / A, so resistance increases with length and decreases with area.
Q15. The unit of electrical conductance is the:
A) Ohm
B) Siemens
C) Henry
D) Farad
Answer: B
Rationale: Conductance is the reciprocal of resistance, measured in siemens (S).
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COMPLETE QUESTIONS AND CORRECT DETAILED ANSWERS
WITH RATIONALES | BRAND NEW VERSION!
SECTION 1: ELECTRICAL THEORY & FUNDAMENTALS (Questions 1–50)
Q1. What is the SI unit of electrical resistance?
A) Volt
B) Ampere
C) Ohm
D) Watt
Answer: C
Rationale: The ohm (Ω) is the SI unit of resistance. It is defined as the resistance
between two points when one volt produces one ampere.
Q2. Ohm's Law states that:
A) Power equals voltage times current
B) Voltage equals current times resistance
C) Current equals voltage times resistance
D) Resistance equals voltage times current
Answer: B
Rationale: V = I × R, the fundamental relationship in electrical circuits.
Q3. A circuit has 120 volts applied and draws 5 amperes. What is the resistance?
A) 24 Ω
B) 600 Ω
C) 0.0417 Ω
D) 125 Ω
Answer: A
Rationale: R = V / I = = 24 Ω.
Q4. The power dissipated in a resistor can be calculated using which formula?
A) P = I²R
1
,B) P = V²/R
C) P = VI
D) All of the above
Answer: D
Rationale: All three are equivalent forms derived from Ohm's Law.
Q5. A 100-watt light bulb is connected to a 120V source. What current does it
draw?
A) 0.833 A
B) 1.2 A
C) 8.33 A
D) 12 A
Answer: A
Rationale: I = P/V = 100/120 = 0.833 A.
Q6. What is the equivalent resistance of two 10 Ω resistors in series?
A) 5 Ω
B) 10 Ω
C) 20 Ω
D) 100 Ω
Answer: C
Rationale: Series resistances add: R_total = R1 + R2 = 10 + 10 = 20 Ω.
Q7. What is the equivalent resistance of two 10 Ω resistors in parallel?
A) 5 Ω
B) 10 Ω
C) 20 Ω
D) 100 Ω
Answer: A
Rationale: Parallel: 1/R_total = 1/10 + 1/10 = 2/10 => R_total = 5 Ω.
Q8. Kirchhoff's Voltage Law states that:
A) The sum of currents entering a node equals the sum of currents leaving
2
,B) The sum of voltages around a closed loop is zero
C) Power is conserved in a circuit
D) Voltage is directly proportional to current
Answer: B
Rationale: KVL: the algebraic sum of all voltages in a closed loop equals zero.
Q9. Kirchhoff's Current Law states that:
A) The sum of voltages around a closed loop is zero
B) The sum of currents entering a node equals the sum leaving
C) Current is inversely proportional to resistance
D) Power equals voltage times current
Answer: B
Rationale: KCL: charge conservation – at a node, total current in = total current
out.
Q10. What is the color code for a resistor with bands: Brown, Black, Red, Gold?
A) 100 Ω ±5%
B) 1,000 Ω ±5%
C) 10,000 Ω ±5%
D) 1,000 Ω ±10%
Answer: B
Rationale: Brown=1, Black=0, Red=multiplier ×100 => 10×100 = 1000 Ω,
Gold=±5%.
Q11. A resistor has a value of 4.7 kΩ with a tolerance of ±10%. What are the
minimum and maximum possible resistance values?
A) 4.23 kΩ to 5.17 kΩ
B) 4.0 kΩ to 5.4 kΩ
C) 4.23 Ω to 5.17 Ω
D) 4.7 kΩ exactly
Answer: A
Rationale: 10% of 4.7k = 0.47k; min = 4.7-0.47 = 4.23k; max = 4.7+0.47 = 5.17k.
3
, Q12. Which of the following materials has the highest electrical conductivity?
A) Copper
B) Silver
C) Aluminum
D) Gold
Answer: B
Rationale: Silver has the highest conductivity of all metals, but copper is more
commonly used due to cost.
Q13. What is the temperature coefficient of resistance for most metals?
A) Positive
B) Negative
C) Zero
D) Infinite
Answer: A
Rationale: Metals have a positive temperature coefficient – resistance increases
with temperature.
Q14. A conductor's resistance is directly proportional to its:
A) Cross-sectional area
B) Length
C) Temperature
D) Both B and C
Answer: B
Rationale: R = ρ L / A, so resistance increases with length and decreases with area.
Q15. The unit of electrical conductance is the:
A) Ohm
B) Siemens
C) Henry
D) Farad
Answer: B
Rationale: Conductance is the reciprocal of resistance, measured in siemens (S).
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