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Capacitors

JEE Main level, single correct, medium

20 of 180

Question 20 of 180

A resistor 'R' and $2 \mu \mathrm{F}$ capacitor in series is connected through a switch to $200 \mathrm{~V}$ direct supply. Across the capacitor is a neon bulb that lights up at $120 \mathrm{~V}$ . Calculate the value of $R$ to make the bulb light up $5 \mathrm{~s}$ after the switch has been closed. $\left(\log _{10} 2.5=0.4\right)$

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Answer: (B) $2.7 \times 10^6 \Omega$

V_c=E\left(1-e^{-t / R c}\right)

1-e^{-t / R c}=\frac{120}{200}=\frac{3}{5}

\Rightarrow R=\frac{5}{1.84 \times 10^{-6}}=2.7 \times 10^6 \Omega

JEE Main question paper PDF

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JEE Main 2025 Apr 2 Shift 1 question paper

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JEE Main Physics practice question on Capacitors (Capacitance), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.