Question 11:
Show how you would connect three resistors, each of resistance 6 Ω, so that the
combination has a resistance of (i) 9 Ω, (ii) 4 Ω.
Answer:
If we connect the resistors in series, then the equivalent resistance will be the
sum of the resistors, i.e., 6 Ω + 6 Ω + 6 Ω = 18 Ω, which is not desired. If we
connect the resistors in parallel, then the equivalent resistance will be
Hence, we should either connect the two resistors in series or parallel.
(i) Two resistors in parallel
Two 6 Ω resistors are connected in parallel. Their equivalent resistance will be
The third 6 Ω resistor is in series with 3 Ω. Hence, the equivalent resistance of the
circuit is 6 Ω + 3 Ω = 9 Ω.
(ii) Two resistors in series
Two 6 Ω resistors are in series. Their equivalent resistance will be the sum
6 + 6 = 12 Ω
The third 6 Ω resistor is in parallel with 12 Ω. Hence, equivalent resistance will
be
Therefore, the total resistance is 4 Ω.
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