BMST - Basic Math and Science Electrical Circuits and Ohm's Law Questions and Answers 5 — Questions and Answers
Question 1: What is the equivalent resistance of three 12 Ω resistors connected in parallel?
- 36 Ω
- 12 Ω
- 6 Ω
- 4 Ω (Correct answer)
Correct answer: 4 Ω
For identical resistors in parallel, R_total = R/n = 12/3 = 4 Ω.
Question 2: A 9 V battery is connected to a circuit. The current measured is 0.5 A. What is the resistance?
- 4.5 Ω
- 9 Ω
- 18 Ω (Correct answer)
- 4 Ω
Correct answer: 18 Ω
R = V/I = 9/0.5 = 18 Ω.
Question 3: Which component in a circuit is used to protect against excess current?
- Capacitor
- Inductor
- Fuse (Correct answer)
- Transformer
Correct answer: Fuse
A fuse contains a wire that melts and breaks the circuit when current exceeds a safe level.
Question 4: In a circuit, voltage is 15 V and power consumed is 45 W. What is the current?
- 1 A
- 2 A
- 3 A (Correct answer)
- 4 A
Correct answer: 3 A
Using P = VI, I = P/V = 45/15 = 3 A.
Question 5: What is the SI unit of electric current?
- Volt
- Ohm
- Watt
- Ampere (Correct answer)
Correct answer: Ampere
Electric current is measured in Amperes (A), named after André-Marie Ampère.
Question 6: A 100 Ω resistor and a 400 Ω resistor are in parallel across a 20 V source. What is the total current from the source?
- 0.1 A
- 0.2 A
- 0.25 A (Correct answer)
- 0.3 A
Correct answer: 0.25 A
I₁ = 20/100 = 0.2 A; I₂ = 20/400 = 0.05 A; total = 0.25 A.
Question 7: Which of the following increases the electrical resistance of a wire?
- Decreasing the wire's length
- Increasing the wire's cross-sectional area
- Using a material with lower resistivity
- Increasing the wire's length (Correct answer)
Correct answer: Increasing the wire's length
Resistance is directly proportional to length (R = ρL/A), so a longer wire has greater resistance.
BMST - Basic Math and Science Electrical Circuits and Ohm's Law Questions and Answers 5
What is the equivalent resistance of three 12 Ω resistors connected in parallel?