# Q. In the given circuit the internal resistance of the 18 V cell is negligible. If $R_1 = 400 \; \Omega , R_3 = 100 \Omega$ and $R_4 = 500 \; \Omega$ and the reading of an ideal voltmeter across $R_4$ is 5V, then the value $R_2$ will be : JEE Main JEE Main 2019

Solution:

## $V_{4} = 5V$ $i_{1} = \frac{V_{4}}{R_{4}} = 0.01 A$ $V_{3} = i_{1} R_{3} = 1V$ $V_{3} +V_{4} = 6V = V_{2}$ $V_{1} + V_{3} + V_{4} = 18 V$ $V_{1} = 12V$ $i = \frac{V_{1} }{R_{1}} = 0.03 Amp .$ $i_{2} = 0.02 Amp V_{2} = 6V$ $R_{2} = \frac{V_{2} }{i_{2}} = \frac{6}{0.02} = 300 \Omega$ You must select option to get answer and solution

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