IV Characteristics of an LED E-practical
Introduction
This experiment plots the IV characteristics of a diode; that is, you plot how the current changes when you change the voltage (the I is for current, and the V is for voltage).
Realistic experimental technique
E-practicals are 3d, highly realistic emulations based on a blend of theory and the actual practicals, giving an authentic experience of doing the actual practical in a laboratory. Students operate the apparatus, make measurements and obtain their own results. It is designed to reproduce the experience of performing the practical rather than simply demonstrating the underlying physics. Like a real experiment, it can be done badly. Careless setup or measurements can produce poor results, so students have to apply experimental technique and take care with their measurements.
Useful when laboratory access is limited
Ideal for preparation before a practical, revision afterwards, missed practicals, home study, or demonstrating an experiment when setting up the real apparatus isn't practical.
Works directly in a browser
No installation is required. Windows, Mac and suitable mobile devices can run the WebGL e-practical.
See it in Action
This shows how the e-practical can be used. In particular it shows how the student or teacher interacts with the apparatus and how the interaction can be controlled using the mouse or the alternative on-screen controls.
What students do
-
Switch on the power.
-
Vary the resistance of the variable resistor (sometimes called a potentiometer or even just a pot) this will change the current flowing through the device.
-
To see the light from the LED you may turn down the room’s lighting by scrolling over the light control on the far wall.
-
Take readings at every 0.1 volt. Note that the right-hand meter is set to display micro amps.
-
To get readings for negative voltages unplug the LED (switch the power off and click on the LED) and reconnect it so that its connections are swapped. The voltages this time count as negative as the LED is now connected the other way around.
-
Plot a graph of current in amps on the Y-axis and volts on the X-axis for the entire range of voltage readings. You should see an L shaped plot with the current zero through all negative values until the diode switches on at some positive value.
What you get
The application is supplied as a PowerPoint which provides background, a synopsis of what the student will learn, a description of the Physics involved, a description of the apparatus, the independent and dependent variables, the method, a link to the interactive online e-practical, analysis of the results and further discussion.
E-practical
Runs in a modern web browser. No software installation required. Recommended or desktops but will run successfully on tablets of medium to large size with a browser that supports WebGL.
School/Department licence £9.99
Valid for 1 year