A series combination of resistors is the one in which resistors are connected end by the end. One terminal of the resistor connects to the other terminal of the resistor and the chain continues.

On the other hand in the parallel circuit, all parallel resistors have one terminal shorted at one point, while other terminal shorted at other points.

Given below is the list of Series and Parallel resistors MCQ.

## MCQ on Series-Parallel Resistors

Three series resistors have an equivalent resistance of 15 ohms. The first resistor has a resistance of 3 ohms, While the second has 5 ohms. What’s the resistance of the third resistor:

- 5 ohms
- 6 ohms
- 7 ohms
- 8 ohms

Correct answer: 3. 7 ohms

Explanation: Let equivalent resistance is Req = 15 ohms

R1 = 3 ohms & R2 = 5 ohms R3 = X

Req = R1 + R2 + R3

Req = 3 + 5 + X

X = 15 – 3 – 5 = **7 ohms** which is correct answer

*Good to know: Ohm’s is SI unit of resistance*

A series circuit having two series resistors has 5 mA current when connected to a 10 V source. The resistance of the first resistor is 1.5 kohms. What is the resistance of the second resistor:

- 0.5 kohms
- 1 kohms
- 1.5 kohms
- Can’t predict

Correct answer: 1. 0.5 kohms

From Ohm’s law: I = V/R; Or R = V/I

For the series circuit of present case R = R1 + R2

R1 + R2 = V/I = 10 V/5 mA

R1 + R2 = 2 kohm

1.5 kohm + R2 = 2 kohm

**R2 = 0.5 kohm** which is correct answer

Four resistors (all having resistance 5 ohms) should be connected in which way to obtain R(eq) = 5 ohms:

- Sum all
- One in parallel to sum of three
- Two in series are parallel to other two in series
- Two in parallel to series of other two

Correct answer: 3. Two in series are parallel to other two in series

Explanation: R + R || R + R

5 Ω + 5 Ω || 5 Ω + 5 Ω

10 Ω || 10 Ω = 5 Ω

MCQ on different Electrical Engineering Topics