Current Through A P-N Junction

Full Wave Rectifier

Definition: The current that flows across a P-N junction in the presence of a reverse bias voltage.
Symbol: Is
Value: Usually in the range of nanoamperes (nA)

Definition: The voltage that must be applied across a P-N junction to prevent the flow of current when it is reverse biased.
Symbol: V0
Value: Typically around 0.7 volts for silicon diodes and 0.3 volts for germanium diodes.

Definition: The voltage applied across a P-N junction in the forward direction to allow the flow of current.
Symbol: Vf
Value: Above 0.7 volts for silicon diodes and above 0.3 volts for germanium diodes.

Definition: The voltage applied across a P-N junction in the reverse direction to prevent the flow of current.
Symbol: Vr
Value: The magnitude of Vr should be greater than the junction potential barrier (V0).

Definition: The current that flows across a P-N junction when it is forward biased.
Symbol: If
Equation: If = Is(e^(Vf/Vt) - 1)
Vt represents the thermal voltage (approximately 26 mV at room temperature)

Definition: The current that flows across a P-N junction when it is reverse biased.
Symbol: Ir
Equation: Ir = Is(e^(Vr/Vt))
Note: As Vr increases, Ir also increases exponentially.

Definition: A circuit that converts an alternating current (AC) into a direct current (DC) signal.
Working principle: Rectifies both halves of the input waveform.
Types: Center-tapped full wave rectifier and Bridge rectifier.

Higher efficiency compared to half-wave rectifier (twice the frequency of output signal)
Output waveform is smoother (less ripple)
Utilizes both halves of the input waveform, providing a higher average voltage.
Suitable for high power applications.

Power supplies: Used to convert AC power to DC power for electronic devices.
Battery chargers: Charges batteries efficiently using rectified DC.
Audio systems: Converts AC audio signals to DC for amplification and processing.
Light dimmers: Converts AC voltage to adjustable DC voltage for controlling lighting intensity.
Motor speed control: Converts AC to DC to control the speed of DC motors.

Ampere’s circuital law: Describes the relation between magnetic field and electric current.
Magnetic field due to a straight conductor: B = (μ0 * I) / (2 * π * r)
Magnetic field due to a circular loop: B = (μ0 * I) / (2 * r)
Magnetic field due to a solenoid: B = μ0 * N * I

Induced EMF: The electromotive force (EMF) induced in a circuit due to a changing magnetic field.
Faraday’s law: The magnitude of induced EMF is directly proportional to the rate of change of magnetic flux through a circuit.
Equation: ε = - dΦ / dt
Lenz’s law: The direction of induced current is such that it opposes the change in magnetic field.

Self-inductance (L): The ability of a coil or conductor to produce an induced EMF due to a changing current.
Inductive reactance (XL): The opposition offered by an inductor to the flow of alternating current.
Equation: XL = 2πfL
Unit: Ohm (Ω)

Capacitance (C): The ability of a capacitor to store electric charge.
Capacitive reactance (XC): The opposition offered by a capacitor to the flow of alternating current.
Equation: XC = 1 / (2πfC)
Unit: Ohm (Ω)

Average power: The average value of the power delivered or dissipated in an AC circuit.
Apparent power (S): The product of the RMS voltage and RMS current in an AC circuit.
Real power (P): The power actually consumed or dissipated in an AC circuit.
Reactive power (Q): The power alternately absorbed and returned by inductive and capacitive loads.
Power factor (PF): The ratio of real power to apparent power.

Transformer: An electrical device that transfers electric energy between two or more circuits through electromagnetic induction.
Principle: Consists of two or more coils wound on a common core.
Step-up transformer: Increases the voltage from primary to secondary coil.
Step-down transformer: Decreases the voltage from primary to secondary coil.
Turns ratio: The ratio of the number of turns in the primary coil to the number of turns in the secondary coil.

Power distribution: Used to step up or step down the voltage in power transmission networks.
Electrical appliances: Used in various household appliances to convert voltage levels.
Electronic devices: Used in power supplies to provide suitable voltage and current levels.
High voltage transmission: Used to step up the voltage for long-distance transmission to reduce power losses.
Electrical isolation: Used to provide galvanic isolation between input and output circuits for safety and noise reduction.