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What is a Diode? An electronic component that allows the current flow in one direction only. It has with two electrodes called the anode and the cathode. Most diodes are made with semiconductor materials such as silicon, germanium .

Application of diode• Rectification :-

A rectifier changes AC (Alternating Current) to DC (Direct Current ) This is the most important application of diodes.

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Types of Diodes

• Normal Diodes• Light-Emitting Diodes (LEDs)• Schottky Diodes• Zener Diodes

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How a diode works

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Forward Operation

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In forward operation the anode connected to the positive electrode of the source and the cathode connected to the negative electrode of the source. In this situation the current flows in the circuit.

The current flows in the Circuit.

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Reverse Operation

In reverse operation the anode connected to the negative electrode of the source and the cathode connected to the positive electrode of the source.

No current ( very small ) flows in in the circuit.

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curve for a real diode.

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Forward and Reverse Operation

• Practical Exercise :-

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Partner Work

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Partner Work

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In short sentence:- Q1 :- Define a diode ?

A diode is a electronic component that allows the current flow in one direction only.

Q2 :- Draw a symbol of diode ?

Q3 :- what is the difference between forward biased and reverse biased ?In forward biased the current flows in the circuit.In reverse biased no current flows in the circuit.

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Example ( 1 ) :- Example ( 1 ) :-

Assume the diode in the circuit below is ideal. Determine the value of ID if :a) VA = 5 volts (Forward Bias) b) VA = -5 volts (Reverse Bias)

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Solution-: a) With VA > 0 the diode is in forward bias and is acting like a perfect conductor so: ID = VA / RS = 5 V / 50 = 0.1 Ab) With VA < 0 the diode is in reverse bias and is acting like a perfect insulator, therefore no current can flow and ID = 0.

Group Work

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Group Work

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Assume the diode in the circuit below is ideal. Determine the value of ID if :a) VA = 10 v (Forward Bias) b) VA = -10 v (Reverse Bias)

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Group Work

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Solution-: a) With VA > 0 the diode is in forward bias and is acting like a perfect conductor so: ID = VA / RS = 10 V / 80 = 0.125 Ab) With VA < 0 the diode is in reverse bias and is acting like a perfect insulator, therefore no current can flow and ID = 0.

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