3 resistors of 5 ohm each are connected, 2 in parallel and the third in series to the others. What is the total resistance of the configuration.
When two resistors with resistance R1 and R2 are connected in parallel, the equivalent resistance of the configiration is given by 1/R = (1/R1 + 1/R2). And for two resistors R1 and R2 connected in series the equivalent resistance is R = R1 + R2.
Of the 3 resistors of 5 ohm each two are connected in parallel. The equivalent resistance of these resistors R where 1/R = 1/5 + 1/5 = 2/5, or R = 5/2 = 2.5 ohm.
The third resistor is connected in series with these two. This is equivalent to two resistors, one of 5 ohm and another of 2.5 ohm connected in series. The equivalent resistance is R = 5 + 2.5 = 7.5 ohm
The equivalent resistance of the configuration of the 3 resistors of 5 ohm each is 7.5 ohm.
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