# Series and Parallel Circuits Questions and Answers pdf [MCQs]

Series and Parallel Circuits Questions and Answers pdf [MCQs]: we will discuss the chapter Parallel Circuit from Subject Electricity Engineering.

## Parallel Circuit MCQs| Parallel Circuit Quiz

### What is parallel circuit?

A parallel circuit is an electrical circuit configuration where multiple components, such as resistors, are connected side by side, sharing the same two connection points. In a parallel circuit, each component is connected directly across the voltage source or power supply, forming separate paths for the flow of electric current.

In a parallel circuit, the components are connected in such a way that the voltage across each component is the same. This is because each component has its own dedicated path to the power source. Additionally, the total current entering the parallel circuit is divided among the different branches or paths, with the sum of the branch currents equaling the total current entering the circuit.

One characteristic of a parallel circuit is that the total resistance decreases as more resistors are added. This is because the presence of multiple paths for current flow reduces the overall resistance. The equivalent resistance of resistors connected in parallel can be calculated using the formula: 1/RTotal = 1/R1 + 1/R2 + 1/R3 + … + 1/Rn, where R1, R2, R3, and so on represent the resistances of the individual components.

In a parallel circuit, if one component fails or is removed, the other components will continue to operate independently. This is because each component has its own separate path to the power source.

Parallel circuits are commonly used in various electrical systems, such as home wiring, electronic devices, and power distribution networks, to provide different electrical components with the same voltage while allowing independent current flow through each component.

## Multiple Choice Questions on Series and Parallel Circuits

#### 1. In a parallel circuit, the total resistance:

a) Increases as more resistors are added

b) Decreases as more resistors are added

c) Remains the same regardless of the number of resistors

d) Cannot be determined

Answer: c) Remains the same regardless of the number of resistors

Explanation: In a parallel circuit, the total resistance is calculated using the formula: 1/RTotal = 1/R1 + 1/R2 + 1/R3 + … + 1/Rn. Since the resistors are connected in parallel, the reciprocal of the total resistance is the sum of the reciprocals of the individual resistances. As more resistors are added in parallel, the sum of the reciprocals increases, but when you take the reciprocal of the sum, it remains the same. Therefore, the total resistance remains the same regardless of the number of resistors.

#### 2. If three identical resistors (R) are connected in parallel, the equivalent resistance is:

a) 3R

b) R/3

c) R/9

d) R + R + R

Explanation: When resistors are connected in parallel, the equivalent resistance is given by the formula: 1/RTotal = 1/R1 + 1/R2 + 1/R3 + … + 1/Rn. Since the three resistors are identical, you can substitute R for each resistance. Simplifying the equation, you get 1/RTotal = 1/R + 1/R + 1/R, which simplifies to 1/RTotal = 3/R. Taking the reciprocal of both sides gives RTotal = R/3, which is the equivalent resistance.

#### 3. In a parallel circuit, if one resistor is removed or becomes open, what happens to the total resistance?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

Explanation: In a parallel circuit, if one resistor is removed or becomes open (infinite resistance), the total resistance decreases. This is because the removal of a resistor reduces the number of paths available for current to flow. With fewer paths, the overall resistance decreases.

#### 4. When two resistors (R1 and R2) are connected in parallel, the total resistance is given by:

a) R1 + R2

b) R1 – R2

c) 1/(R1 + R2)

d) R1 × R2

Explanation: The formula for calculating the total resistance of two resistors connected in parallel is: 1/RTotal = 1/R1 + 1/R2. Taking the reciprocal of both sides gives RTotal = 1/(1/R1 + 1/R2), which simplifies to RTotal = 1/(R1R2 / (R1 + R2)). Further simplifying, you get RTotal = (R1 + R2)/(R1R2), which is equivalent to 1/(R1 + R2).

#### 5. In a parallel circuit, the voltage across each resistor is:

a) Equal to the total voltage of the circuit

b) Different for each resistor

c) Zero

d) Cannot be determined

Answer: a) Equal to the total voltage of the circuit

Explanation: In a parallel circuit, each resistor has the same voltage across it. This is because all resistors in a parallel configuration are connected across the same two points, and the voltage across a parallel combination is the same as the total voltage applied to the circuit.

6. In a parallel circuit, the current:

a) Splits evenly among the branches

b) Increases as more resistors are added

c) Decreases as more resistors are added

d) Remains the same regardless of the number of resistors

Answer: a) Splits evenly among the branches

Explanation: In a parallel circuit, the current divides or splits among the branches. Each branch or resistor provides a different path for the current to flow. The current flowing into the parallel combination is split into fractions, with each branch carrying a portion of the total current.

7. Two resistors, R1 and R2, are connected in parallel. If R1 has a resistance of 4 ohms and R2 has a resistance of 6 ohms, what is the equivalent resistance of the combination?

a) 2 ohms

b) 3 ohms

c) 4 ohms

d) 10 ohms

8. If a parallel circuit has three resistors with resistance values of 3 ohms, 4 ohms, and 5 ohms respectively, what is the total resistance of the circuit?

a) 1.2 ohms

b) 3.6 ohms

c) 4.8 ohms

d) 12 ohms

9. In a parallel circuit, if one resistor is removed or becomes open, what happens to the total current?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

Answer: c) It remains the same

10. When two resistors (R1 and R2) are connected in parallel, the equivalent resistance is given by:

a) R1 + R2

b) R1 – R2

c) 1/R1 + 1/R2

d) R1 × R2

## MCQ on series and parallel circuits for class 10

11. In a parallel circuit, if one resistor has a higher resistance compared to the others, what happens to the current flowing through that resistor?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

12. In a parallel circuit, the total current is equal to:

a) The sum of the currents through each resistor

b) The average of the currents through each resistor

c) The difference between the currents through each resistor

d) None of the above

Answer: a) The sum of the currents through each resistor

13. If four identical resistors (R) are connected in parallel, the equivalent resistance is:

a) R/4

b) R/2

c) 2R

d) 4R

14. In a parallel circuit, the voltage across each resistor is:

a) The same for each resistor

b) Different for each resistor

c) Zero

d) Cannot be determined

Answer: a) The same for each resistor

15. If a parallel circuit has a total resistance of 10 ohms and a current of 2 amperes, what is the voltage across each resistor?

a) 0.4 volts

b) 2 volts

c) 5 volts

d) 20 volts

16. In a parallel circuit, the total current is:

a) Shared equally among the resistors

b) Determined by the largest resistor in the circuit

c) Determined by the smallest resistor in the circuit

d) Independent of the resistors in the circuit

Answer: a) Shared equally among the resistors

17. Two resistors, R1 and R2, are connected in parallel. If R1 has a resistance of 8 ohms and R2 has a resistance of 12 ohms, what is the equivalent resistance of the combination?

a) 3.2 ohms

b) 4.8 ohms

c) 6 ohms

d) 20 ohms

18. If a parallel circuit has three resistors with resistance values of 6 ohms, 10 ohms, and 15 ohms respectively, what is the total resistance of the circuit?

a) 3.6 ohms

b) 5.5 ohms

c) 31 ohms

d) 60 ohms

19. In a parallel circuit, if one resistor is removed or becomes open, what happens to the total voltage?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

Answer: c) It remains the same

20. When three resistors (R1, R2, and R3) are connected in parallel, the equivalent resistance is given by:

a) R1 + R2 + R3

b) 1/(1/R1 + 1/R2 + 1/R3)

c) R1 × R2 × R3

d) R1 – R2 – R3

Answer: b) 1/(1/R1 + 1/R2 + 1/R3)

## Series and Parallel Circuits Questions and Answers PDF Class 10

21. In a parallel circuit, if one resistor has a lower resistance compared to the others, what happens to the current flowing through that resistor?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

22. In a parallel circuit, the total power is equal to:

a) The sum of the powers through each resistor

b) The average of the powers through each resistor

c) The difference between the powers through each resistor

d) None of the above

Answer: a) The sum of the powers through each resistor

23. If three identical resistors (R) are connected in parallel, the equivalent resistance is:

a) 3R

b) R/3

c) R/9

d) R + R + R

24. In a parallel circuit, the total current is 4 amperes, and one of the resistors has a current of 1 ampere. What is the current flowing through the other resistors?

a) 1 ampere

b) 2 amperes

c) 3 amperes

d) Cannot be determined

25. If a parallel circuit has a total resistance of 20 ohms and a voltage of 10 volts, what is the current flowing through each resistor?

a) 0.5 amperes

b) 1 ampere

c) 2 amperes

d) 5 amperes

26. In a parallel circuit, the total resistance is always:

a) Greater than the resistance of any individual resistor

b) Less than the resistance of any individual resistor

c) Equal to the sum of the resistances of all the resistors

d) Equal to the resistance of the smallest resistor in the circuit

Answer: b) Less than the resistance of any individual resistor

27. Two resistors, R1 and R2, are connected in parallel. If R1 has a resistance of 6 ohms and R2 has a resistance of 3 ohms, what is the equivalent resistance of the combination?

a) 9 ohms

b) 4 ohms

c) 2 ohms

d) 1.5 ohms

28. If a parallel circuit has three resistors with resistance values of 8 ohms, 12 ohms, and 16 ohms respectively, what is the total resistance of the circuit?

a) 3.2 ohms

b) 4 ohms

c) 6 ohms

d) 16 ohms

29. In a parallel circuit, if one resistor is removed or becomes open, what happens to the total current?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

30. When four resistors (R1, R2, R3, and R4) are connected in parallel, the equivalent resistance is given by:

a) R1 + R2 + R3 + R4

b) 1/(1/R1 + 1/R2 + 1/R3 + 1/R4)

c) R1 × R2 × R3 × R4

d) R1 – R2 – R3 – R4

Answer: b) 1/(1/R1 + 1/R2 + 1/R3 + 1/R4)

## Series and Parallel Circuits Questions and Answers GCSE

31. In a parallel circuit, if one resistor has a higher resistance compared to the others, what happens to the voltage across that resistor?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

32. In a parallel circuit, the total power is equal to:

a) The sum of the powers through each resistor

b) The average of the powers through each resistor

c) The difference between the powers through each resistor

d) None of the above

Answer: a) The sum of the powers through each resistor

33. If four identical resistors (R) are connected in parallel, the equivalent resistance is:

a) R/4

b) R/2

c) 2R

d) 4R

34. In a parallel circuit, the total current is 5 amperes, and one of the resistors has a current of 2 amperes. What is the current flowing through the other resistors?

a) 2 amperes

b) 3 amperes

c) 4 amperes

d) Cannot be determined

35. If a parallel circuit has a total resistance of 10 ohms and a current of 2 amperes, what is the voltage across each resistor?

a) 0.4 volts

b) 1 volt

c) 2 volts

d) 5 volts

36. In a parallel circuit, if one resistor has a resistance of 3 ohms and another resistor has a resistance of 6 ohms, what is the equivalent resistance of the combination?

a) 9 ohms

b) 2 ohms

c) 1.5 ohms

d) 0.5 ohms

37. In a parallel circuit, the total current is 8 amperes, and there are three resistors connected. If the current through one resistor is 2 amperes, what is the current through the other two resistors?

a) 4 amperes each

b) 2 amperes each

c) 3 amperes each

d) 8 amperes each

38. When three resistors (R1, R2, and R3) are connected in parallel, and R1 has a resistance of 6 ohms, R2 has a resistance of 3 ohms, and R3 has a resistance of 2 ohms, what is the equivalent resistance of the combination?

a) 1 ohm

b) 2 ohms

c) 3 ohms

d) 4 ohms

39. In a parallel circuit, if one resistor becomes shorted or has a very low resistance, what happens to the total current?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

40. When four resistors (R1, R2, R3, and R4) are connected in parallel, and R1 has a resistance of 10 ohms, R2 has a resistance of 20 ohms, R3 has a resistance of 30 ohms, and R4 has a resistance of 40 ohms, what is the equivalent resistance of the combination?

a) 100 ohms

b) 40 ohms

c) 24 ohms

d) 7.5 ohms

41. In a parallel circuit, if one resistor has a higher resistance compared to the others, what happens to the current flowing through that resistor?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

42. In a parallel circuit, if one resistor becomes disconnected or open, what happens to the total resistance?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

43. If three resistors (R1, R2, and R3) are connected in parallel, and R1 has a resistance of 8 ohms, R2 has a resistance of 12 ohms, and R3 has a resistance of 20 ohms, what is the equivalent resistance of the combination?

a) 2.56 ohms

b) 4.8 ohms

c) 5 ohms

d) 8 ohms

44. In a parallel circuit, the total current is 10 amperes, and one of the resistors has a resistance of 4 ohms. What is the current flowing through the other resistors?

a) 2 amperes

b) 4 amperes

c) 6 amperes

d) 8 amperes

45. If a parallel circuit has a total resistance of 5 ohms and a current of 2 amperes, what is the voltage across each resistor?

a) 0.2 volts

b) 0.4 volts

c) 1 volt

d) 2 volts

46. In a parallel circuit, if one resistor has a resistance of 2 ohms and another resistor has a resistance of 5 ohms, what is the equivalent resistance of the combination?

a) 7 ohms

b) 3 ohms

c) 1.4 ohms

d) 0.4 ohms

47. In a parallel circuit, the total current is 12 amperes, and there are four resistors connected. If the current through one resistor is 3 amperes, what is the current through the other three resistors?

a) 3 amperes each

b) 4 amperes each

c) 2 amperes each

d) 1 ampere each

48. When three resistors (R1, R2, and R3) are connected in parallel, and R1 has a resistance of 4 ohms, R2 has a resistance of 6 ohms, and R3 has a resistance of 8 ohms, what is the equivalent resistance of the combination?

a) 1.33 ohms

b) 2 ohms

c) 2.67 ohms

d) 18 ohms

49. In a parallel circuit, if one resistor becomes shorted or has a very low resistance, what happens to the total resistance?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

50. When four resistors (R1, R2, R3, and R4) are connected in parallel, and R1 has a resistance of 8 ohms, R2 has a resistance of 12 ohms, R3 has a resistance of 16 ohms, and R4 has a resistance of 20 ohms, what is the equivalent resistance of the combination?

a) 2.86 ohms

b) 5 ohms

c) 6.67 ohms

d) 10 ohms

51. In a parallel circuit, if one resistor has a higher resistance compared to the others, what happens to the current flowing through that resistor?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

52. In a parallel circuit, if one resistor becomes disconnected or open, what happens to the total current?

a) It increases

b) It decreases

c) It remains the same

d) It cannot be determined

Answer: c) It remains the same

53. If three resistors (R1, R2, and R3) are connected in parallel, and R1 has a resistance of 10 ohms, R2 has a resistance of 15 ohms, and R3 has a resistance of 20 ohms, what is the equivalent resistance of the combination?

a) 4 ohms

b) 5 ohms

c) 7.5 ohms

d) 45 ohms

#### Benefits of Parallel Circuit

Parallel circuits offer several benefits in electrical systems. Here are some of the advantages of using parallel circuit configurations:

1. Independent Operation: In a parallel circuit, each component operates independently. If one component fails or is removed from the circuit, the other components continue to function without interruption. This is advantageous in situations where the failure of one component should not affect the operation of others.
2. Constant Voltage: In a parallel circuit, each component receives the same voltage across its terminals. This ensures that each component operates at its rated voltage, regardless of the number or characteristics of other components in the circuit. It allows for consistent performance and avoids voltage drops across components.
3. Division of Current: In a parallel circuit, the total current supplied by the source is divided among the individual branches or paths. Each component receives the current it requires, allowing them to operate independently. This feature is useful when different components need different levels of current.
4. Reduced Total Resistance: When resistors or other components are connected in parallel, the total resistance of the circuit decreases. This is because each component provides an additional path for current to flow, effectively reducing the resistance of the overall circuit. It allows for increased current flow and can help in distributing power evenly across components.
5. Easy Component Addition/Removal: Parallel circuits allow for easy addition or removal of components without affecting the rest of the circuit. Each component has its own connection to the power source, so adding or removing a component does not disrupt the operation of other components. This flexibility is beneficial for maintenance, upgrades, or modifications in electrical systems.
6. Fault Isolation: In a parallel circuit, if a fault occurs in one branch or component, it does not affect the rest of the circuit. Other branches continue to function normally, ensuring uninterrupted operation of the system. This fault isolation feature enhances the reliability and robustness of the overall electrical system.

Overall, parallel circuits provide flexibility, reliability, and independent operation for electrical systems. They are widely used in various applications, ranging from simple household wiring to complex electronic devices and power distribution networks.