Which one of the following is the resistance that must be placed parallel with `12Omega` resistance t obtain a cmbined resistance of `4Omega` ?

Options

A. `2Omega`
B. `4Omega`
C. `6Omega`
D. `8Omega`

Answer

C

Explanation

Let `R Omega` Resistance placed parallel with `12Omega`
Then equivalent resistance `=(1)/(R)+(1)/(12)=(1)/(4)`
`implies" "(12+R)/(12R)=(1)/(4)`
`implies" "48+4R=12R`
`implies" "8R=48`
`:." "R=6Omega`