Question

plz solve this as soon as possible!!!

Answer 1

remove 8 ohm since it will not affect the circuit

Answer 2

Answer: The equivalent resistance will be 8 ohm and 4 ohm.

Explanation:  

Let us considered $R_{1}= 6\Omega$, $R_{2}= 12\Omega$, $R_{3}= 6\Omega$, $R_{4}= 12\Omega$ and $R_{5}= 8\Omega$

Case (I)-

When switch S is open

Then, $R_{1}$ and  $R_{2}$ in parallel and  $R_{3}$ and  $R_{4}$ in parallel but  $R_{5}$ will not active

Therefore, the equivalent resistance is between points A and B

For first case, when $R_{1}$ and  $R_{2}$ in parallel

$R = 4\Omega$

For second case, when $R_{3}$ and  $R_{4}$ in parallel

$R' = 4\Omega$

Now, $R$ and  $R'$ in series

$R''=R+R'$

$R''=8\Omega$

Case (II)-

When switch S is close  

Then, $R_{1}$ and  $R_{2}$ in parallel and  $R_{3}$ and  $R_{4}$ in parallel and  $R_{5}$  in also parallel

Therefore, the equivalent resistance is between points A and B

For first case, when $R_{1}$ and  $R_{2}$ in parallel

$R = 4\Omega$

For second case, when $R_{3}$ and  $R_{4}$ in parallel

$R' = 4\Omega$

Now, $R$ and  $R'$ in series

$R''=R+R'$

$R''=8\Omega$

$\dfrac{1}{R'''}=\dfrac{1}{R''}+\dfrac{1}{R_{5}}$

$\dfrac{1}{R'''}= 4$

Hence, The equivalent resistance will be 8 ohm and 4 ohm.