Question

Write a Report on the following –

1) Describe waveform characteristics for sinusoidal waveforms

2) What is a Diode? Explain forward and reverse biased characteristics of a diode with circuit diagrams.

3) What is a rectifier? Explain half wave and full wave rectifier with circuit diagrams.

Answer 1

Question 1. Describe waveform characteristics for sinusoidal waveform.

Answer: Sinusoidal waveform is define as Curve which will trace out a smooth repetitive oscillations .It is a waveform whose amplitude is always proportional to the sine of its displacement angle,

Sine wave is mathematically define as

Where A = Amplitude ,w = Angular frequency and Phi = phase

Some important characteristics of Sinusoidal waveform is

1. As per the definition Sine waves are very smooth varying without and sudden change in amplitude.

2. As we know that number of cycle in one second is known as frequency and we said that sine wave are repetitive cycle.therefore sinusoid are repetitive in pattern.

3. Here the slope ( i.e. Amplitude ) is not constant .It also varies in sinusoidal pattern.

4. As we say the amplitude is not constant .In real life the sinusoidal signals vary with respect to time .One cycle means 0 degrees to 360 degrees and half cycle means 0 to 180 degrees.

Question 2 .What is a Diode? Explain forward and reverse biased characteristics of a diode with circuit diagrams.

Answer : Diode is an electronic device which has two terminals. It is typically a semiconductor device which allow flow of current in one direction. It has high considerably infinite resistance in one direction and low considerably zero direction in other direction.As we say diode is semiconductor device . A P-N junction diode is made of P-type and N-type semiconductor and it is a simplest semiconductor device which allow current to flow in one direction.Diode is a non linear element whose I-V characteristics has exponential Current-Voltage relationship.Therefore we cannot describe the operation of diode simply by using ohm's law

When Positive end is connected to P side and negative end is connected to N side then the diode is in forward region. And when positive end is connected to N side and Negative end is connected to P side then it is reverse bias .

When positive voltage is applied there will excess amount of electrons and holes with extra energy which tries to cross the junction and due to this width of depletion region decreased. When negative voltage is applied i.e reverse bias the free electrons are pulled away from the junction and width of depletion region increased .This way the resistance will increase and decrease accordingly

with this theory we can draw V-I characteristics of P-N diode as shown below

It has three bias

Zero Bias

Forward Bias

Reverse bias

When no voltage is applied the diode is in zero bias means it is stand still

When the diode is forward bias as we say earlier positive voltage is applied to P-type and Negative voltage is applied to N-type material and if this voltage becomes more than the potential barrier ( It is nothing but a region in a particular junction there we need more force to cross the junction).For silicon it is 0.7 V and for germanium it is 0.2 to 0.3 V. Then the diode conducts and current increases exponentially

when the diode is reverse bias means the positive voltage is applied to N side and negative voltage is applied to P side .In this type due to Positive voltage applied to N side the N type material attracts electrons to the positive electrode and away form the junction and same way holes in the P-type attracted to Negative electrode.Due to this the junction width will become wide and the diode is act as a insulator and prevent current from flowing . Ideally zero current will flow during reverse bias but practically small amount of leakage current will flow through it which is of very small level like micro amps.