Building the combinations and measuring with the ammeter:
Steps:
1. I installed a 1N914 diode on the breadboard and connected the voltmeter across it in parallel so that the voltage across the diode could be measured.
2. Next, I connected a 1kΩ and a variable resistor in series with the diode so that the necessary connections were made.
3. Then, I applied a 5V voltage supply at the free end of the 1kΩ resistor (to limit the current to safe values), and grounded the free end of the diode as shown in the schematic diagram.
4. Then by changing the values of the variable resistor, the corresponding current flowing through the circuit was measured with the help of an ammeter connected in series with the circuit.
5. Finally, for the varying values of currents the corresponding voltages were read from the voltmeter that was connected across the diode.
|
Resistance used (in kΩ)
'R'
|
Current ( in mA )
'I'
|
Voltage (in V)
'VD'
|
|
10
|
.398
|
.576
|
|
30
|
.145
|
.525
|
|
56
|
.080
|
.493
|
|
75
|
.059
|
.480
|
Table 3 - Represents the recorded values of voltage across the diode and current flowing through it for different values of the resistor used.
Note:
I used different values of the resistor instead of the variable resistor, due to unavailability of the variable resistors. This did not alter the circuit behavior so the results obtained were accurate.
Inference:
1. As can be seen from the Table 3, above as the value of the resistor increases the current flowing through the diode decreases and so does the voltage across it.
2. When the values in the table are analyzed I noticed that as the current decreases the voltage across the diode decreases but not in proportion with the change in current. Therefore it can be inferred that the diode does not have resistor-like properties and thus does not obey Ohm's law.
Graph:
1. To obtain the behavior of the voltage and the corresponding current I plotted the graph of V vs. Ito display how the diode diverges from the resistor-like behavior: