Question

In the circuit shown, the effective resistance between the points a and b is
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Answer 1

Given that,

Resistance $R_{1}=6\ \Omega$

Resistance $R_{2}=18\ \Omega$

Resistance $R_{3}=6\ \Omega$

Resistance $R_{4}=18\ \Omega$

Resistance $R_{5}=6\ \Omega$

According to Wheatstone bridge,

The middle resistance is neglect. Because the current does not flow in middle leg.

So, Resistance R₃  is neglected.

We need to calculate the effective resistance between the points a and b

Using Wheatstone bridge formula for effective resistance

$R_{e}=\dfrac{R_{1}\times R_{2}}{R_{4}+R_{5}}$

Put the value into the formula

$R_{e}=\dfrac{6\times18}{6+18}$

$R_{e}=4.5\ \Omega\approx5\ \Omega$

Hence, The effective resistance between the points a and b is 5 Ω.