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Saturday, 31 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumApplication

JEE Main 9 January 2020, Shift 2, Physics Q12

Question 12 of 75 in this shift, Physics question 12 of 25, Section A.

Two identical capacitors A and B, charged to the same potential 5V are connected in two different circuits as shown below at time t=0t=0. If the charge on capacitors A and B at time t=CRt=CR is QAQ_A and QBQ_B respectively, then (Here ee is the base of natural logarithm)

The figure, in words

Two circuits, each a charged capacitor (A, B) in series with a resistor R and a diode. In circuit A the diode is oriented so that it blocks discharge; in circuit B the diode is reversed (conducting), so the capacitor discharges through R.
  1. (1)QA=VC, QB=CVQ_A = VC,\ Q_B = CV
  2. (2)QA=CV2, QB=VCeQ_A = \frac{CV}{2},\ Q_B = \frac{VC}{e}
  3. (3)QA=VCe, QB=CV2Q_A = \frac{VC}{e},\ Q_B = \frac{CV}{2}
  4. (4)QA=VC, QB=VCeQ_A = VC,\ Q_B = \frac{VC}{e}Official answer

Official answer

Option 4

NTA final key (Jan 2020).

Chapter
Electrostatic Potential and Capacitance
Topic
RC Circuits
Idea tested
RC Circuits with Ideal Diodes

Same topic in other shifts

All RC Circuits questions
  1. 5 Apr 2026, Shift 2 · Q37Under steady state condition the potential difference across the capacitor in the circuit is __________ V.MediumSingle correctHas a figure
  2. 5 Apr 2024, Shift 1 · Q55The electric field between the two parallel plates of a capacitor of 1.5 μF1.5\ \mu\mathrm{F} capacitance drops to one third of its initial…MediumNumerical value
  3. 1 Feb 2024, Shift 2 · Q41A galvanometer (G) of 2 Ω2\,\Omega resistance is connected in the given circuit. The ratio of charge stored in C1C_1 and C2C_2 is :MediumDiagram basedHas a figure
  4. 1 Feb 2024, Shift 2 · Q56In an electrical circuit drawn below the amount of charge stored in the capacitor is ________ μ\muC.MediumNumerical valueHas a figure
  5. 8 Apr 2023, Shift 1 · Q49In this figure the resistance of the coil of galvanometer G is 2 Ω2\ \Omega. The emf of the cell is 4 V4\ \mathrm{V}. The ratio of potential…MediumDiagram basedHas a figure
  6. 29 Jun 2022, Shift 2 · Q37A capacitor is discharging through a resistor RR. Consider in time t1\mathrm{t_1}, the energy stored in the capacitor reduces to half of…MediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.