Question

How much current will flow through the wire AB ?

Answer 1

Explanation:

Given:

Four resistances ,

Two passing through A having resistance of 6 ohm and 12 ohm respectively.

Two passing through B having resistance of 12 ohm and 6 ohm respectively.

potential difference (V)=80V

To find :

Current (I)

Formulas:(used)

Rs=R1+R2

1/Rp=1/R1+1/R2

V=I/R

Solution:

The effective resistance of resistors passing through A is

Rs= R1+R2

Rs= (6+12)ohm

Rs=18 ohm ...... (1)

[ Take (1) as 1/R1]

The effective resistance of resistors passing through B is

Rs= R1+R2

Rs=(12+6)ohm

Rs=18ohm ....... (2)

[Take (2) as 1/R2]

The effective resistance of resistors passing through A&B is

1/Rp = 1/R1+1/R2

1/Rp= 1/18+1/18

therefore,

Rp= 18/2 .......

( the inverse of effective resistance is equal to the inverse of individual resistance)

therefore,

Rp= 9 ohm

The current flowing is,

V=IR ....... ( Ohm's law)

thus,

I=V/R

I=80/9

I=8.88 ohm

i.e.

I~9 ohm