Electronics Tutorial #4: Ohms Law

If you want to build your own electronic circuits, one law you must learn and know how to use is Ohms law. Ohms law lets you calculate the current and voltage through and across a resistor. The basic equation that Ohms law states is that voltage is equal to the product of current and resistance. In equation form:

Equation 1: V= IR

If you know the voltage across a resistor and the current through a resistor you can compute the value of the resistor. Similarly, if you know the resistor value and the current through the resistor you can compute the voltage across the resistor.  For example if you put 2 Volts across a 1 Ohm resistor, from Ohms law you calculate that the current is 1 Ampere.

If you don't want to do the hand calculations required for Ohms law, you can always use a circuit simulator. The LTSpice circuit simulator, is a free simulator, that you can use to calculate the voltage across and the current through a resistor. In the LTSpice circuit schematic below, a 10 Volt battery is placed across a 1000 Ohm resistor. Using Ohms law, you can calculate that the current through the resistors would be 0.01 Ampere or 10 mA. A mA (milliamp) is 1/1000th of an Ampere.

LTSPICE Ohms Law Circuit Simulation

There are many advantages of using the LTSpice circuit simulator to analyze a circuit. One advantage is that it eliminates calculation errors. The second advantage is that you can analyze complex circuits, that would take hours of hand calculations, in seconds.  The third advantage is that it facilitates learning and allows you to build intuition about circuit design.

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