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Question #43451

Difficulty: 8/10 | 🟢 Free

The Question

A full-wave rectifier operates from a 50 Hz50 \text{ Hz} AC mains supply and delivers a constant direct current I0=28 mAI_0 = 28 \text{ mA} to a load. The filtering circuit uses a parallel-plate capacitor with a non-linear ferroelectric dielectric. Due to the non-linear energy density locality in the dielectric, the total charge qq stored on the capacitor depends on the voltage VV across it as q(V)=C0V+kV2q(V) = C_0 V + k V^2, where C0=50 \muFC_0 = 50 \text{ \mu F} and k=5 \muF/Vk = 5 \text{ \mu F/V}. The peak voltage reached by the capacitor during each charging cycle is V0=10 VV_0 = 10 \text{ V}. Assuming the discharge time is approximately equal to the time interval between consecutive voltage peaks, what is the peak-to-peak ripple voltage ΔV\Delta V across the load?

Options

  • A.

    2.0 V2.0 \text{ V}

  • B.

    2.8 V2.8 \text{ V}

  • C.

    5.6 V5.6 \text{ V}

  • D.

    1.9 V1.9 \text{ V}

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Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Multi-Concept_Bridge

Master problems that require linking physics and math concepts to solve complex competitive questions.

Concepts Behind This Question

Rectifier Ripple Factor|Energy Density Locality|Integration

Why This Question Is Tricky

Common Mistakes

Students often memorize the standard ripple voltage formula ΔV=IΔtC\Delta V = \frac{I \Delta t}{C} assuming a linear, constant capacitance.

In this problem, the dielectric is non-linear, meaning the capacitance is a function of voltage.

Applying the standard formula with either the base capacitance C0C_0, the secant capacitance Ceq=q/VC_{eq} = q/V, or the tangent capacitance Cdiff=dq/dVC_{diff} = dq/dV leads to incorrect results.

The trap tests whether the student can abandon the shortcut formula, revert to the fundamental conservation of charge principle (I=−dq/dtI = -dq/dt), and solve the resulting non-linear state equation for the discharge cycle.

Quick Facts About This Question

Question Information

SubjectPhysics
ChapterSemiconductor Electronics: Materials, Devices, and Simple Circuits - Class 12
ConceptRectifier Ripple Factor
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree