Semiconductor Electronics: Materials, Devices and Simple Circuits

Physics · Class 12

Simulation · Physics · Class 12

From ac to steady dc

"From ac to steady dc" is a free, interactive Class 12 Physics simulation for NEET and JEE, built on the lesson "Half-wave and full-wave rectifiers" in Semiconductor Electronics: Materials, Devices and Simple Circuits. Switch between half-wave and full-wave, then add a filter capacitor. The diodes are treated as ideal. Half-wave passes one half-cycle (50 pulses a second from 50 Hz), full-wave both (100). A large capacitor across the load charges to the peak and discharges slowly through RL, so a large time constant C × RL gives nearly steady dc. JEE Main asked 46 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).

From the lesson Half-wave and full-wave rectifiers in Semiconductor Electronics: Materials, Devices and Simple Circuits. Change the values and watch what happens.

From ac to steady dcPhysics · Class 12

In JEE Main

42 shifts analysed

46 questions from Semiconductor Electronics: Materials, Devices and Simple Circuits across the 42 JEE Main shifts Lumi has analysed (2017–2026).

See the past questions

The idea behind it

NCERT §14.7

  • Because a diode conducts only when forward biased, an alternating voltage across it drives current only in that part of the cycle. Turning ac into one-way voltage like this is rectification, and the circuit is a rectifier.
  • Half-wave rectifier: one diode in series with a load resistor RL across a transformer secondary (terminals A and B). When A is positive the diode conducts; when A is negative it is reverse biased and blocks.
  • The reverse saturation current is so small it counts as zero, so the output is a train of positive half-cycles with gaps: still varying, but in one direction only.
  • The diode's reverse breakdown voltage must be well above the peak ac voltage of the secondary, or the negative half-cycle would break it down.
  • Full-wave rectifier: two diodes whose p-sides go to the two ends of a centre-tapped secondary. Their n-sides are joined, and the output is taken between that common point and the centre tap.
  • Each diode sees only half of the total secondary voltage. When A is positive with respect to the centre tap, B is negative (out of phase): D1 conducts and D2 blocks.
  • In the other half-cycle A is negative and B positive, so D2 conducts and D1 blocks. Current flows through RL in the same direction both times, giving output in both halves of the cycle.
  • Full-wave rectification uses both halves, so it is more efficient than half-wave. A second full-wave circuit, the bridge, uses four diodes and needs no centre tap.
  • Output pulses: half-wave gives one per input cycle and full-wave two. For 50 Hz input, the output frequency is 50 Hz for half-wave and 100 Hz for full-wave (Exercise 14.6).

Questions

3 answers

What does the "From ac to steady dc" simulation show?
Switch between half-wave and full-wave, then add a filter capacitor. The diodes are treated as ideal.
Does JEE Main ask questions from Semiconductor Electronics: Materials, Devices and Simple Circuits?
Yes. JEE Main asked 46 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
Is this simulation free?
Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Half-wave and full-wave rectifiers" in Semiconductor Electronics: Materials, Devices and Simple Circuits (Class 12 Physics).

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