Mechanical Aptitude Basic Electrical Circuits Questions and Answers — Questions and Answers
Question 1: In a simple series circuit, if a 12-volt battery is connected across two resistors of 6 ohms and 3 ohms, what is the total current flowing through the circuit?
- 0.75 A
- 1.33 A (Correct answer)
- 2.0 A
- 4.0 A
Correct answer: 1.33 A
According to Ohm's Law (V=IR), current (I) is voltage (V) divided by total resistance (R). In a series circuit, the total resistance is the sum of individual resistances (R_total = R1 + R2). So, R_total = 6Ω + 3Ω = 9Ω. The current is then I = 12V / 9Ω = 1.33 A.
Question 2: Which of the following components is specifically designed to oppose the flow of electric current?
- Capacitor
- Inductor
- Diode
- Resistor (Correct answer)
Correct answer: Resistor
A resistor is an electrical component that implements electrical resistance as a circuit element. Its primary function is to reduce current flow, adjust signal levels, divide voltages, etc. Capacitors store energy, inductors store energy in a magnetic field, and diodes allow current to flow in only one direction.
Question 3: Three light bulbs are connected in parallel to a power source. If one of the bulbs burns out, what happens to the other two bulbs?
- They both go out.
- They both get brighter.
- They both get dimmer.
- They remain lit with the same brightness. (Correct answer)
Correct answer: They remain lit with the same brightness.
In a parallel circuit, each component is connected across the same two points, providing multiple paths for the current. If one bulb burns out (creating an open circuit in its branch), the other branches are unaffected and will continue to draw the same current from the source, so the remaining bulbs stay lit with unchanged brightness.
Question 4: A circuit has a voltage of 24V and a resistance of 6Ω. What is the power consumed by the circuit?
- 4 Watts
- 96 Watts (Correct answer)
- 144 Watts
- 0.25 Watts
Correct answer: 96 Watts
The formula for electrical power (P) can be expressed in several ways, including P = V²/R. Using the given values: P = (24V)² / 6Ω = 576 / 6 = 96 Watts.
Question 5: What is the primary function of a fuse in an electrical circuit?
- To store electrical charge
- To increase the voltage
- To protect the circuit from excessive current (Correct answer)
- To convert AC to DC
Correct answer: To protect the circuit from excessive current
A fuse is a safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level. This protects the circuit's components from damage.
Question 6: If you have two resistors, R1 and R2, connected in parallel, how do you calculate the total equivalent resistance (Rt)?
- Rt = R1 + R2
- Rt = (R1 * R2) / (R1 + R2) (Correct answer)
- Rt = R1 - R2
- Rt = 1/R1 + 1/R2
Correct answer: Rt = (R1 * R2) / (R1 + R2)
For two resistors in parallel, the total resistance is the product of the two resistances divided by their sum. The general formula for parallel resistors is 1/Rt = 1/R1 + 1/R2 + ... For only two resistors, this simplifies to Rt = (R1 * R2) / (R1 + R2).
Mechanical Aptitude Basic Electrical Circuits Questions and Answers
In a simple series circuit, if a 12-volt battery is connected across two resistors of 6 ohms and 3 ohms, what is the total current flowing through the circuit?