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Home Electrical and Electronics Analog Electronics Study of V-I Characteristics of a Diode
Analog Electronics Lab Experiments

Study of V-I Characteristics of a Diode



Aim

Study of V-I Characteristics of a Diode.

Apparatus Required:

Diode Characteristics Kit, Power Supply, Ammeter (0-20mA), Voltmeter (0-20V), Connecting Leads.

Brief Theory:A P-N junction is known as Semiconductor diode or Crystal diode. It is the combination of P-type & N-type Semiconductor. This offers nearly zero resistance to current on forward biasing & nearly infinite Resistance to the flow of current when in reverse biased.

Forward biasing:When P-type semiconductor is connected to the +ve terminal and N-type to –ve terminal of voltage source. Nearly zero resistance is offered to the flow of current.

Reverse biasing:When P-type semiconductor is connected to the –ve terminal and N-type to +ve terminal. Nearly zero current flow in this condition.

Circuit Diagram:

circuit-diagram

Procedure:

  1. Connect the circuit as shown in fig.
  2. Switch on the power supply.
  3. Vary the value of input dc supply in steps.
  4. Note down the ammeter & voltmeter readings for each step.
  5. Plot the graph of Voltage Vs Current.
  6. Connect the circuit as shown in fig.

Observation Table:

S.No. When Diode Is Forward Biased/Current(m A)/Voltage(V) When Diode Is Reverse Biased/Current (µA)/Voltage(V)
1
2
3
4
5
6

Graph:

graph

Result:The graph has been plotted between voltage and current.

Discussion:The diode doesn’t conduct in RB state and conduct in FB state.

Precautions:

  1. Always connect the voltmeter in parallel & ammeter in series as shown in fig.
  2. Connection should be proper & tight.
  3. Switch ‘ON’ the supply after completing the circuit
  4. DC supply should be increased slowly in steps
  5. Reading of voltmeter & Ammeter should be accurate.

Quiz:

Q:Define semiconductor diode?

A:A PN – junction is called semiconductor diode.

Q:Define depletion layer?

A:The region having uncompensated acceptor and donor ions.

Q:What do you mean by forward biased?

A:When +ve terminal of battery is connected to P side & -ve terminal to N side of diode.

Q:What do you mean by reverse biased?

A:When +ve terminal of battery is connected to N side & -ve terminal to P side of diode.

Q:Define Knee voltage?

A:The forward voltage at which current through the junction starts increasing rapidly.

Q:Define breakdown voltage?

A:Reverse voltage at which PN junction breaks down with sudden rise in reverse current.

Q:Define max. Forward current?

A:It is highest instantaneous forward current that a PN junction can conduct without damage to Junction.

Q:Define max. Power rating?

A:Max. Power that can be dissipated at junction without damage to it.












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