# Basic Electronics

This post is an addendum for using the Falstad program.  I thought if posts are kept small understanding how it works will be easier.  There was quite a bit of information, albeit simplified, included in the Falstad post.  In this post, I will attempt to explain a very basic but very essential law of how electronic circuits operate.

The law is called Ohm’s law.  This is a mathematical relationship among resistance, voltage and current.  Before getting into the math part, I am going to explain how these components affect the flow of electricity in the circuit.  Resistors act to slow the current flowing in the circuit.  As an analogy, consider you have a water tank that has a pipe coming out of it.  The level of water in the tank would be like the voltage, the high the level, the higher the voltage.  The pipe is like a resistor, the smaller the diameter of the pipe, the higher the resistance and conversely, the larger the diameter, the lower the resistance.  The speed of the water as it flows through the pipe is analogous to the current.  If you can visualize this water tank example then you can visualize what electrons are going to do in a circuit.  Electricity is just the flow of electrons.

Lastly the math part.  The attached image is a handy tool to remember the equation for Ohm’s law, V (voltage) = R (resistance) times I (current).  Using this equation if you know two of the values, you can determine the unknown value.  For example if voltage is 12 volts and the resistance is 1 Ohm then by applying the equation you find that the current is 12 Amps.  When using this law V needs to be in volts so if you had a millivolt it must be expressed as .001 in the equation, a millivolt is one one thousandth of a volt or 1/1000.  Resistors are rated in Ohms and current is rated in amps.

The terminology is the hardest part, the math is fairly easy.  A little on the terminology.  Here’s a chart.

deka-   10^1         deci-     10^(-1)

hecto-  10^2        centi-   10^(-2)

kilo-      10^3        milli-    10^(-3)

mega-  10^6        micro-  10^(-6)

giga-     10^9        nano-    10^(-9)

tera-      10^12      pico-     10^(-12)

Using the law you can calculate the value of the components to combine to give you the desired output.