# What is the resultant resistance of the circuit given above

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A. 8Ω

B. 11Ω

C. 4Ω

D. 3.6Ω

A

## EXPLANATION…

If a number of resistors are arranged in series, the effective or resultant resistance of them combined is simply addition of the resistance of each resistor.

But if a number of resistors are connected in parallel, the reciprocal of the effective or resultant resistance will be the simple addition of the reciprocal of the resistance of each resistor. Please note that reciprocal here means inverse.

If R1, R2, R3, and R4 are connected in series, then:

Resultant resistance = R1 + R2 + R3 + R4

If they are connected in parallel, then:

1/Resultant resistance = 1/R1 + 1/R2 + 1/R3 + 1/R4

In the above connection, two of the 2ohms resistors are connected in parallel, we would have to resolve them first, so that the resultant of these two resistors will now be in series with the 4 and 3 ohms resistors.

Resultant resistance of the two 2ohms resistors will be calculated thus:

1/R = ½ + ½ ,

Therefore, 1/R = 2/2 = 1/1, R = 1

We now have three resistors in series which are, 3 ohms, 1 ohms, and 4 ohms.

Final resultant resistance will be = 3 + 1 + 4 = 8 ohms.

### Now for the right answer to the above question:

1. Option A is correct.
2. Option B is incorrect.
3. C is incorrect.
4. D is not the correct answer.