JEE PYQ: Current Electricity Question 58
Question 58 - 2019 (09 Jan 2019 Shift 2)
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 of $R_2$ will be:
(1) $300,\Omega$
(2) $450,\Omega$
(3) $550,\Omega$
(4) $230,\Omega$
Show Answer
Answer: (1)
Solution
Across $R_4$: $V_4 = 5$ V, $i_4 = \frac{5}{500} = 0.01$ A. $V_3 = i_4 R_3 = 1$ V. $V_1 + V_3 + V_4 = 18$, $V_1 = 12$ V. $i = \frac{V_1}{R_1} = 0.03$ A. $i = i_1 + i_2$. $i_2 = 0.03 - 0.01 = 0.02$ A. $R_2 = \frac{V_1}{i_2} = \frac{6}{0.02} = 300,\Omega$.
BETA
