Here, compared to Exp-4b, we have removed the LED from the circuit and replaced 470 Ohm resistor with a 1K Ohm one. The book asks the reader to put the multimeter between the battery and the potentiometer. Even though EC calculates the current in the circuit by default, I have added the Amp-meter for illustration purposes in order to follow what is being done in the book. Everything is pretty simple here. With the Pot. @ 1K ohm and the resistor = 1k ohm we have a total of 2k ohm in the circuit with power supply of 9V. So I = E/R = 9 / 2000 = 4.5mA. Ohm's law at work! You can play around with the values of the Pot. & compare the results to what you see in the book.
