In the given circuit the internal resistance of the 18V cell is negligible. If R1=400Ω,R3=100Ω and R4=500Ω and the reading on an ideal voltmeter across R4 is 5V, then the value of R2 will be
A
230Ω
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B
300Ω
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C
450Ω
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D
550Ω
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Solution
The correct option is B300Ω
Reading of voltameter across R4, V4=5V
So, current throgh R4, i1=V4R4=0.01A
Voltage across R3, V3=i1R3=0.01×100=1V
Total voltage V3+V4=6V=V2
From circuit, we can write- V1+V3+V4=18V ⇒V1=12V i=V1R1=0.03A
Using KCL,