In the given circuit the internal resistance of the 18 V cell is negligible. If `R_(1)=400 Omega` and the reading of an ideal voltmeter across `R_(4)` is 5V, then the value of `R_(2)` will be :

Options

A. `230 Omega`
B. `450 Omega`
C. `300 Omega`
D. `550 Omega`

Explanation

`R_3=100 and R_4=500 Omega`
`V_4` (Reading of an ideal voltmeter across `R_4)=5V`
Now `V_3` (Voltage across `R_3)=1V`
And `V_2` (voltage across `R_2`)=6V As `V_2=V_3+V_4`
Voltage across `R_1=12V implies` i(through all) `=12/400`
=30mA
`i_3=10mA`
So `i_2=20mA`
Now `V_2` (Voltage across `R_2`)=`20mA times R_2`
`6=20mA times R_2 implies R_2=300 Omega`