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Question
In the circuit shown below in Fig, calculate the value of x if the equivalent resistance between A and B is 4 Ω.
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Solution
r1 = 4 Ω
r2 = 8 Ω
r3 = x Ω
r4 = 5 Ω
Rs1 = r1+r2
= 4 + 8
= 12 Ω
Rs2 = r3 + r4
= x + 5 Ω
`1/"R" =1/"Rs"_1 + 1/"Rs"_2`
`1/4 = 1/12 + 1/(5+x)`
`1/6=1/(5+x)`
x = 1 Ω
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