Phys 165 Module 8 Exam Questions &
Answers to Pass the Exam (),
100% Verified
1. What is the relationship between the cross-sectional area of a wire and its
resistance?
A) Directly proportional
B) Inversely proportional
C) No relationship
D) It depends on the material
Correct Answer: B
Rationale: Resistance is inversely proportional to the cross-sectional area of a wire. A
wider wire provides more path for electrons to flow, thus reducing resistance .
2. True or False: Direct current reverses direction at regular intervals.
A) True
B) False
Correct Answer: B
Rationale: This statement is false. Direct current (DC) flows in one direction.
Alternating current (AC) is what reverses direction at regular intervals .
3. Which of the following statements is TRUE for a collection of resistors
connected in series? Assume the resistance of each resistor is different.
A) The current through each resistor is the same.
B) The equivalent resistance is equal to the sum of the individual resistances.
C) The total voltage across the circuit is equal to the sum of the individual voltages.
D) All of the above are true.
Correct Answer: D
Rationale: In a series circuit, current is constant, total resistance is the sum of individual
resistances, and total voltage is the sum of the individual voltage drops .
,4. True or False: Kirchhoff's Loop Rule states that the sum of the potential
differences around any closed loop in an electric circuit is always greater than the
current in the circuit.
A) True
B) False
Correct Answer: B
Rationale: This statement is false. Kirchhoff's Loop Rule states that the sum of the
electric potential differences (voltages) around any closed loop is zero .
5. Which of the following statements is TRUE for a collection of resistors
connected in parallel?
A) The sum of the current through each resistor is equal to the total current of the
circuit.
B) The equivalent resistance is equal to the sum of the individual resistances.
C) The total voltage of the circuit is equal to the sum of the voltages across each resistor.
D) A, B, and C are true.
Correct Answer: A
Rationale: In a parallel circuit, current divides among branches, while voltage is the
same across each branch. The total current is the sum of the branch currents .
SECTION 2: CIRCUIT PROBLEM SOLVING
6. A 6.0-volt battery is connected in a circuit with a 4.0-ohm resistor. Find the
current through the circuit. Show your work.
Answer: 1.5 Amps
Rationale: Using Ohm's Law, V = IR → I = V/R = 6.0 V / 4.0 Ω = 1.5 A .
7. A 20-Ω and 10-Ω resistor are wired in series. Calculate the equivalent resistance.
Answer: 30 Ohms
Rationale: For series resistors: RT = R1 + R2 = 20 Ω + 10 Ω = 30 Ω .
8. A 5.00-Ω and 11.0-Ω resistor are wired in parallel. Calculate the equivalent
resistance.
, Answer: 3.45 Ohms
Rationale: For parallel resistors: 1/RT = 1/5.00 + 1/11.0 = 0.290; RT = .290 = 3.45
Ω.
9. What is the resistivity of a wire that is 5.25 m long, has a cross-sectional area of
4.24 x 10⁻⁵ m², and a resistance of 0.196 Ω?
Answer: 1.58 Ω·m
Rationale: Using the resistivity formula, ρ = R·A / L = (0.196 Ω × 4.24 × 10⁻⁵ m²) / 5.25
m = 1.58 Ω·m .
10. What is the maximum value of AC current when the effective value of current
is 8.42 A?
Answer: 11.9 Amps
Rationale: The max current (Imax) is the effective current multiplied by √2: Imax = 8.42
A × √2 ≈ 11.9 A .
SECTION 3: MAGNETISM AND ELECTROMAGNETISM (Questions 11-20)
11. The magnetic field lines of a bar magnet exit from the ________ pole and enter
through the ________ pole.
A. South, North
B. North, South
C. East, West
D. West, East
Correct Answer: B
Rationale: Magnetic field lines are defined to travel from the north pole to the south
pole outside the magnet. Inside the magnet, they go from the south pole back to the
north.
12. What is the effect of increasing the current through a solenoid on the strength
of its magnetic field?
A. The magnetic field strength decreases.
B. The magnetic field strength increases proportionally.
C. The magnetic field strength remains unchanged.
D. The magnetic field reverses direction.
Answers to Pass the Exam (),
100% Verified
1. What is the relationship between the cross-sectional area of a wire and its
resistance?
A) Directly proportional
B) Inversely proportional
C) No relationship
D) It depends on the material
Correct Answer: B
Rationale: Resistance is inversely proportional to the cross-sectional area of a wire. A
wider wire provides more path for electrons to flow, thus reducing resistance .
2. True or False: Direct current reverses direction at regular intervals.
A) True
B) False
Correct Answer: B
Rationale: This statement is false. Direct current (DC) flows in one direction.
Alternating current (AC) is what reverses direction at regular intervals .
3. Which of the following statements is TRUE for a collection of resistors
connected in series? Assume the resistance of each resistor is different.
A) The current through each resistor is the same.
B) The equivalent resistance is equal to the sum of the individual resistances.
C) The total voltage across the circuit is equal to the sum of the individual voltages.
D) All of the above are true.
Correct Answer: D
Rationale: In a series circuit, current is constant, total resistance is the sum of individual
resistances, and total voltage is the sum of the individual voltage drops .
,4. True or False: Kirchhoff's Loop Rule states that the sum of the potential
differences around any closed loop in an electric circuit is always greater than the
current in the circuit.
A) True
B) False
Correct Answer: B
Rationale: This statement is false. Kirchhoff's Loop Rule states that the sum of the
electric potential differences (voltages) around any closed loop is zero .
5. Which of the following statements is TRUE for a collection of resistors
connected in parallel?
A) The sum of the current through each resistor is equal to the total current of the
circuit.
B) The equivalent resistance is equal to the sum of the individual resistances.
C) The total voltage of the circuit is equal to the sum of the voltages across each resistor.
D) A, B, and C are true.
Correct Answer: A
Rationale: In a parallel circuit, current divides among branches, while voltage is the
same across each branch. The total current is the sum of the branch currents .
SECTION 2: CIRCUIT PROBLEM SOLVING
6. A 6.0-volt battery is connected in a circuit with a 4.0-ohm resistor. Find the
current through the circuit. Show your work.
Answer: 1.5 Amps
Rationale: Using Ohm's Law, V = IR → I = V/R = 6.0 V / 4.0 Ω = 1.5 A .
7. A 20-Ω and 10-Ω resistor are wired in series. Calculate the equivalent resistance.
Answer: 30 Ohms
Rationale: For series resistors: RT = R1 + R2 = 20 Ω + 10 Ω = 30 Ω .
8. A 5.00-Ω and 11.0-Ω resistor are wired in parallel. Calculate the equivalent
resistance.
, Answer: 3.45 Ohms
Rationale: For parallel resistors: 1/RT = 1/5.00 + 1/11.0 = 0.290; RT = .290 = 3.45
Ω.
9. What is the resistivity of a wire that is 5.25 m long, has a cross-sectional area of
4.24 x 10⁻⁵ m², and a resistance of 0.196 Ω?
Answer: 1.58 Ω·m
Rationale: Using the resistivity formula, ρ = R·A / L = (0.196 Ω × 4.24 × 10⁻⁵ m²) / 5.25
m = 1.58 Ω·m .
10. What is the maximum value of AC current when the effective value of current
is 8.42 A?
Answer: 11.9 Amps
Rationale: The max current (Imax) is the effective current multiplied by √2: Imax = 8.42
A × √2 ≈ 11.9 A .
SECTION 3: MAGNETISM AND ELECTROMAGNETISM (Questions 11-20)
11. The magnetic field lines of a bar magnet exit from the ________ pole and enter
through the ________ pole.
A. South, North
B. North, South
C. East, West
D. West, East
Correct Answer: B
Rationale: Magnetic field lines are defined to travel from the north pole to the south
pole outside the magnet. Inside the magnet, they go from the south pole back to the
north.
12. What is the effect of increasing the current through a solenoid on the strength
of its magnetic field?
A. The magnetic field strength decreases.
B. The magnetic field strength increases proportionally.
C. The magnetic field strength remains unchanged.
D. The magnetic field reverses direction.
