Greetings from DoCircuits! Let’s start this blog with a simple experiment. Let’s say you’re asked to perform an experiment to find the power dissipated across a diode. Yes, you would connect a voltmeter and ammeter across a forward-biased diode, run the simulation, and take down the voltage and current across the diode. And finally you have to multiply the V and I values to obtain the power. Tedious isn’t it? How about if you were asked to the power dissipation across the diode with respect to the applied voltage? It’s not impossible. Well let’s see how we can do that too.

Let’s see the circuit that we have to rig up. The resistor is 1 kΩ.

After creating the circuit, click on the “Equations” tab to open the following window:

In the bottom of the equation panel you would find the measuring devices that are connected in the circuit, in this case the voltmeter and the ammeter. Above that you have all the mathematical functions and operators that can be used for your equation. The power equation is V * I. This equation can be added to the experiment as shown below:

Then click on “Add” to save the equation.

Clicking on the equation on the right hand column you can either edit the equation or delete it. In addition to that if you want the equation displayed on the grid along with the circuit for easy working, you can click on “Pin to Grid”.

Now vary the input voltage from 0 to 2 V and run the simulation. Plot the variables in the output plot with respect to the voltmeter value:

The plot shows the IV characteristics of the diode as well the power variation as calculated by the equation.

Thus using the mathematical functions available in the equations panel you can plot calculated variables.