Experiment #2: Diodes

In experiment #2 I was asked to identify the anode and cathode of my LED and 1N4007 Diode using my multimeter.

My readings were LED: Anode - OL Forward Bias
Cathode - OL Reverse Bias

1N4007: Anode - 695mV Forward Bias
Cathode - OL Reverse Bias

In able to identify these without a multimeter, on the LED, I would have looked for the longest stem, it being the Anode, and the shorter being the Cathode. For the 1N4007 the end of the Diode which has the gray stripe would be the Cathode and the opposite being the Anode.


Calculate the first value of current flowing through the diode, now measure and check your answer.

Calculated: 5V/1000R = 5mA
Measured: 4.78mA

Is the reading as you had expected?: Yes, I expected to get 5mA if not just slightly less than 5mA.

Calculate the voltage drop across the diode, now measure and check your answer.

Calculated: 695mV ( taken from previous question )
Measured: 665mV

Using the data sheet, What is the maximum value of the current that can flow through the given diode?: 1A

For R = 1KR. What is the maximum value of Vs so that the diode operates in a safe region?
: 1000V

Replace the diode by an LED & calculate the current, then measure and check your answer.

Calculated: 5V/1KR = 5mA
Measured: 3.41mA

What have you observed?: Because the voltage has remained constant and the current has decreased, the Resistance must have increased when I switch the Diode with the LED.