Slide rule for Ohm's law

In this lab we will build a slide rule to calculate the three magnitudes of Ohm's law.


Slide rules were used frequently to perform calculations in technology in the last century. We owe slide rules many designs for airplanes, bridges, and even space rockets.

In the 1970s, with the appearance of the first modern electronic calculators, slide rules gradually fell out of use, until a few years later they could only be found in museums. Despite its use having disappeared, slide rules had several advantages that we can see when using this practice.

Slide rules use logarithms to ensure that multiplication and division operations can be performed with the simple movement of a cursor. Logarithms were discovered in the 17th century and have been a great help in performing calculations ever since until the advent of modern computing in the mid-20th century.

Assembly and use

Slide rule to calculate Ohm's law. PDF format

To carry out this practice, you must print the attached PDF sheet, cut the edges and fold the flaps very precisely. Once the flaps are folded, we will place the cursor inside until we have a rule like the one that can be seen in the previous image.

With the rule already built, the central cursor must be moved to match the data of the problem.

If we know the voltage, we will have to move the mark to the appropriate voltage value and then find the known resistance value or current value, which will coincide with the final value sought.

If we do not know the voltage, the known current and resistance value must be matched in the rules and the mark will indicate the voltage value that solves the problem.