BMST Electrical Circuits and Ohm's Law 3 — Questions and Answers
Question 1: What does a voltmeter measure in a circuit?
- Current through a component
- Resistance of a component
- Potential difference across a component (Correct answer)
- Power consumed by a component
Correct answer: Potential difference across a component
A voltmeter measures the potential difference (voltage) across two points in a circuit.
Question 2: How is an ammeter correctly connected in a circuit?
- In parallel with the component
- In series with the component (Correct answer)
- Across the power supply only
- Between two parallel branches
Correct answer: In series with the component
An ammeter must be connected in series so all current flows through it for accurate measurement.
Question 3: A circuit has two resistors (10 Ω and 40 Ω) in parallel connected to a 20 V source. What current flows through the 10 Ω resistor?
- 0.5 A
- 1 A
- 2 A (Correct answer)
- 4 A
Correct answer: 2 A
Voltage is the same across parallel components, so I = V/R = 20/10 = 2 A.
Question 4: What is the unit of electrical power?
- Volt
- Ampere
- Ohm
- Watt (Correct answer)
Correct answer: Watt
Electrical power is measured in watts (W), where 1 W = 1 joule per second.
Question 5: Which statement best describes Kirchhoff's Current Law (KCL)?
- Voltage drops around a loop sum to zero
- Current entering a node equals current leaving it (Correct answer)
- Resistance increases with temperature
- Power equals voltage times resistance
Correct answer: Current entering a node equals current leaving it
KCL states that the total current entering a junction equals the total current leaving it.
Question 6: A light bulb has a resistance of 240 Ω when connected to a 120 V source. How much current flows?
- 0.25 A
- 0.5 A (Correct answer)
- 2 A
- 4 A
Correct answer: 0.5 A
I = V/R = 120/240 = 0.5 A.
Question 7: What happens to the total resistance when more resistors are added in parallel?
- Total resistance increases
- Total resistance stays the same
- Total resistance decreases (Correct answer)
- Total resistance becomes zero
Correct answer: Total resistance decreases
Adding more parallel paths gives current more ways to flow, reducing the total resistance.
BMST Electrical Circuits and Ohm's Law 3
What does a voltmeter measure in a circuit?