# Series Circuits MCQ (Interview-Exam) Question-Answer

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## Series Circuits MCQ (Interview-Exam) Question-Answer

Q.1 Find the current in the circuit.

A. 2 A

B. 4 A

C. 1 A

D. 3 A

Ans : 2 A

Explanation: I=V/R. Total resistance R = 20+40=60ohm. V=120V. I=120/60=2A.

Q.2 In a series circuit, which of the parameters remain constant across all circuit elements such as resistor, capacitor and inductor etcetera?

A. Current

B. Both voltage and current

C. Voltage

D. None of them

Ans : Current

Q.3 Find the voltage across the 6 ohm resistor.

A. 181.6V

B. 54.48V

C. 150V

D. 27.27V

Ans : 27.27V

Explanation: Total current I=150/(6+12+15)=(150/33)V.

V across 6 ohm = 6*I = 6*(150/33)V = 27.27V.

Q.4 Voltage across the 60ohm resistor is______.

A. 0V

B. 120V

C. 72V

D. 48V

Ans : 0V

Explanation: The 60ohm resistance is shortened because the current always chooses the low resistance path. The voltage in a short circuit is equal to zero, so the voltage across the resistor is 0.

Q.5 What is the value of x if the current in the circuit is 5A?

A. 25 ohm

B. 75 ohm

C. 15 ohm

D. 55 ohm

Ans : 15 ohm

Explanation: Total voltage=sum of voltages across each resistor. =>150=10*5+5*5+5*x. Solving the equation, we get x=15 ohm.

Q.6 If there are two bulbs connected in series and one blows out, what happens to the other bulb?

A. The other bulb stops glowing

B. The other bulb glows with increased brightness

C. The other bulb continues to glow with the same brightness

D. The other bulb also burns out

Ans : The other bulb stops glowing

Q.7 Many resistors connected in series will?

A. Divide the current proportionally

B. Reduce the power to zero

C. Divide the voltage proportionally among all the resistors

D. Increase the source voltage in proportion to the values of the resistors

Ans : Divide the voltage proportionally among all the resistors

Q.8 A voltage across a series resistor circuit is proportional to?

A. The value of the resistance itself

B. The power in the circuit

C. The amount of time the circuit was on for

D. The value of the other resistances in the circuit

Ans : 2 A

Q.9 What happens to the current in the series circuit if the resistance is doubled?

A. It becomes double its original value

B. It becomes infinity

C. It becomes half its original value

D. It becomes zero

Ans : It becomes half its original value

Q.10 What is the voltage measured across a series short?

A. Zero

B. Null

C. Infinite

D. The value of the source voltage

Ans : Zero

## Series Circuits in Electrical Engineering

• Single Path for Current: In a series circuit, all components (resistors, capacitors, inductors, etc.) are connected in a single path, forming a continuous loop.
• Same Current Through All Components: The same current flows through all components in a series circuit. This is a characteristic of series circuits.
• Voltage Divides Across Components: The total voltage supplied is divided among the components in proportion to their resistance. The voltage across each component adds up to the total voltage.
• Resistance Adds Up: The total resistance in a series circuit is the sum of the individual resistances of each component. $$R_{\text{total}} = R_1 + R_2 + \ldots + R_n$$
• Current is Constant: Since there is only one path for current flow, the same current passes through each component. It remains constant throughout the circuit.
• If One Component Fails: If one component in a series circuit fails (opens), the entire circuit is broken, and current cannot flow.
• Applications in Voltage Dividers: Series circuits are often used in voltage divider circuits, where the input voltage is divided into different proportions across resistors.
• Analytical Calculations: Analyzing a series circuit is relatively straightforward using Kirchhoff’s voltage law and Ohm’s law. These laws help in determining the current, voltage, and resistance relationships in the circuit.
• Limited in Practical Applications: While series circuits are useful for certain applications, they are less common in practical electrical systems due to their vulnerability to complete failure if one component malfunctions.
• Battery Cells in Series: Connecting batteries in series increases the total voltage output while maintaining the same current. This configuration is often used to power devices requiring higher voltage.

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