Topics
Electric Charges and Fields
- Electric Charge
- Conductors and Insulators
- Basic Properties of Electric Charge
- Coulomb’s Law
- Forces between Multiple Charges
- Electric Field
- Electric Field Due to a System of Charges
- Physical Significance of Electric Field
- Electric Field Lines
- Electric Flux
- Electric Dipole
- Dipole in a Uniform External Field
- Continuous Charge Distribution
- Gauss’s Law
- Application of Gauss' Law
Electrostatics
Current Electricity
Electrostatic Potential and Capacitance
- Electric Potential and Potential Energy
- Electrostatic Potential
- Electric Potential Due to a Point Charge
- Potential Due to an Electric Dipole
- Potential due to a System of Charges
- Equipotential Surfaces
- Relation Between Electric Field and Electrostatic Potential
- Potential Energy of a System of Charges
- Potential Energy of a Single Charge
- Potential Energy of a System of Two Charges in an External Field
- Potential Energy of a Dipole in an External Field
- Electrostatics of Conductors
- Dielectrics and Polarisation
- Capacitors and Capacitance
- The Parallel Plate Capacitor
- Effect of Dielectric on Capacitance
- Combination of Capacitors
- Energy Stored in a Charged Capacitor
Magnetic Effects of Current and Magnetism
Current Electricity
- Electric Current
- Electric Currents in Conductors
- Ohm's Law
- Drift of Electrons and the Origin of Resistivity
- Mobility of Electrons
- Limitations of Ohm’s Law
- Resistivity of Various Materials
- Temperature Dependence of Resistivity
- Electrical Energy and Power in Conductors
- Cells, EMF, and Internal Resistance
- Cells in Series and in Parallel
- Kirchhoff’s Laws
- Wheatstone Bridge
Electromagnetic Induction and Alternating Currents
Moving Charges and Magnetism
- Electromagnetism
- Magnetic force
- Motion in a Magnetic Field
- Magnetic Field Due to a Current Element, Biot-savart Law
- Magnetic Field on the Axis of a Circular Current-Carrying Loop
- Ampere’s Circuital Law
- Solenoid
- Force Between Two Parallel Currents (Ampere’s Law)
- Torque on a Rectangular Current Loop in a Uniform Magnetic Field
- Circular Current Loop as a Magnetic Dipole
- Moving Coil Galvanometer
- Kirchhoff’s Laws
Electromagnetic Waves
Magnetism and Matter
Electromagnetic Induction
Optics
Dual Nature of Radiation and Matter
Alternating Current
Atoms and Nuclei
Electromagnetic Waves
Electronic Devices
Ray Optics and Optical Instruments
- Ray Optics Or Geometrical Optics
- Reflection of Light by Spherical Mirrors
- Sign Convention for Reflection by Spherical Mirrors
- Focal Length of Spherical Mirrors
- Mirror Equation of Spherical Mirrors
- Refraction of Light
- Total Internal Reflection
- Applications of Total Internal Reflection
- Refraction at a Spherical Surfaces
- Refraction by a Lens
- Power of a Lens
- Combined Focal Length of Two Thin Lenses in Contact
- Refraction of Light Through a Prism
- Optical Instruments
- Microscope and it’s types
- Telescope
- Overview of Ray Optics and Optical Instruments
Wave Optics
- Concept of Wave Optics
- Huygens Principle
- Refraction of a Plane Wave
- Refraction at a Rarer Medium
- Reflection of a Plane Wave by a Plane Surface
- Coherent and Incoherent Addition of Waves
- Interference of Light Waves and Young’s Experiment
- Diffraction of Light
- The Single Slit
- Seeing the Single Slit Diffraction Pattern
- Polarisation of Light
- Overview: Wave Optics
Communication Systems
The Special Theory of Relativity
Dual Nature of Radiation and Matter
- Understanding Dual Nature of Radiation and Matter
- Electron Emission
- Photoelectric Effect - Hertz’s Observations
- Photoelectric Effect - Hallwachs’ and Lenard’s Observations
- Experimental Study of Photoelectric Effect
- Effects of Intensity and Frequency on Photocurrent
- Photoelectric Effect and Wave Theory of Light
- Einstein’s Photoelectric Equation: Energy Quantum of Radiation
- Particle Nature of Light: The Photon
- Wave Nature of Matter
- Overview: Dual Nature of Radiation and Matter
Atoms
Nuclei
Semiconductor Electronics - Materials, Devices and Simple Circuits
Communication Systems
- Detection of Amplitude Modulated Wave
- Production of Amplitude Modulated Wave
- Basic Terminology Used in Electronic Communication Systems
- Sinusoidal Waves
- Modulation and Its Necessity
- Amplitude Modulation (AM)
- Need for Modulation and Demodulation
- Satellite Communication
- Propagation of EM Waves
- Bandwidth of Transmission Medium
- Bandwidth of Signals
The Special Theory of Relativity
- The Special Theory of Relativity
- The Principle of Relativity
- Maxwell'S Laws
- Kinematical Consequences
- Dynamics at Large Velocity
- Energy and Momentum
- The Ultimate Speed
- Twin Paradox
Definition: Rectifier
A rectifier is an electronic circuit that converts alternating current (AC) into direct current (DC) by using one or more p-n junction diodes.
Definition: Half-wave Rectifier
A half-wave rectifier allows only one half of the AC cycle to pass through the load, producing a pulsating DC output.
Definition: Full-wave Rectifier
A full-wave rectifier uses both half cycles of the AC input to produce a more continuous pulsating DC output.
Definition: Filter
A filter is a circuit element or arrangement, often involving a capacitor or inductor, used to smooth the pulsating rectified output.
Definition: Pulsating DC
Pulsating DC is an output that flows in one direction but whose magnitude changes with time.
Half-wave Rectifier
Circuit Idea
A half-wave rectifier generally uses:
- One p-n junction diode
- A load resistance RL
- An AC source, often through a transformer
Working
During the positive half cycle
- The diode is forward-biased.
- Current flows through the load resistance.
- A voltage appears across the load.
During the negative half cycle
- The diode is reverse-biased.
- Current does not flow through the load.
- Output across the load becomes nearly zero.
Result
Only one-half of the AC input is used. Therefore, the output is a unidirectional but pulsating voltage.
Important Point
The half-wave rectifier is simple and inexpensive, but it is less efficient because it uses only one half of the input signal.
Full-wave Rectifier
Working
First half cycle
- One end of the secondary becomes positive relative to the centre tap.
- The corresponding diode becomes forward-biased.
- Current flows through the load in one fixed direction.
Second half cycle
- The other end of the secondary becomes positive relative to the centre tap.
- The second diode conducts.
- Current again flows through the load in the same direction.
Result
Both half cycles contribute to the output. Therefore, the output is more continuous than that of a half-wave rectifier.
Important Point
A full-wave rectifier gives better efficiency and better DC output quality than a half-wave rectifier.
Half-wave vs Full-wave
| Feature | Half-wave Rectifier | Full-wave Rectifier |
|---|---|---|
| Number of diodes | Usually 1 | Usually 2 with centre tap, or 4 in bridge form |
| Use of the AC cycle | Uses one-half cycle only | Uses both half cycles |
| Output quality | More pulsating | Smoother than half-wave |
| Efficiency | Lower | Higher |
| Circuit complexity | Simple | More complex |
| Exam importance | Basic concept question | Frequently asked for comparison and working |
Need of Filtering
The rectifier output is not a perfectly steady DC. It is pulsating, so in many applications it must be smoothed using a filter circuit.
Capacitor Filter
A capacitor connected in the output circuit charges when the output rises and discharges when the output falls. This reduces fluctuations and makes the output voltage smoother.
Inductor Filter
An inductor opposes sudden changes in current and can also help smooth the rectified output.
Time Constant
For a capacitor-input filter, smoothing depends on the time constant:
A large RLC value helps the capacitor hold charge longer, so the output approaches a steady DC.
