Question

the total resistance between A and B is​

Answer 1

Answer:

9/4 ohm

Explanation:

The following circuit, is Wheatstone and bridge. And we know in Wheatstone bridge that if the system is balanced then no current will flow through middle part here its 5 ohm resistor.

Balance condition of Wheatstone bridge is, ratio of one side should be equal to another side.

In this case,

• 2/1 = 6/3 = 2

So we can see that ratio is equal. Hence, the bridge is balanced. And thus no current will flow through that 5 ohm resistor.

Now, we can remove 5 ohm resistor then we see that 1 and 2 ohm are in series whereas 6 and 3 ohm are in series.

We know for series combination,

R = R1+R2

Where R is equivalent resistance of 1 and 2 ohm resistor. And R' is equivalent resistance of 6 and 3 ohm.

So, R = 1+2 = 3 ohm and R' = 6+3 = 9 ohm

Thus, we have now 2 resistors of resistance 9 and 3 ohm parallel to each other.

We also know for parallel combination,

1/Req = 1/R1 + 1/R2

Where Req is equivalent resistance of 9 and 3 ohm resistors which are parallel to each other.

And so putting the values, we get;

• 1/Req = 1/9 + 1/3

• Req = 9×3/9+3

• Req = 27/12

• Req = 9/4 ohm