Tuesday, October 12, 2010

Understanding Ohm's Law (and other equations)

Ohm's Law, I believe, is the most used equation in electronics analysis. It is the fundamental building block for knowing what's going on in any particular circuit.

V = I * R

 V is the potential in Volts (V)
I is the current flow in Amperes (A)
R is the resistance in Ohms (Ω)

So, one Volt of potential is equal to one Ampere of current multiplied by one Ohm of resistance. Using this equation, if you have two know variables you can easily solve for the third.

Let me explain what these variables mean.

Voltage (V)
Voltage is the electric potential of a circuit. Electricity flows like water. If you have two bodies of water, one higher than the other and both connected with a sloping pipe, water would flow from the higher potential body of water to the lower potential body of water. In the diagram below, the water from Tank A should flow towards Tank B because of the potential difference they have.

Current (A)
The electric current in a circuit is the flow of electrons through it. A single electron has a charge of roughly 1.602 x 10 ^-19 Coulombs. One Ampere is equal to one Coulomb divided by one Second.
This is the flow of charge per second. An example would be to measure the amount of water leaving Tank A above and flowing into Tank B per second. That would be the current of water flowing.

Resistance (Ω)
The resistance of a circuit is a measurement of how hard it resists the flow of charge. In our water example above, there are two examples of resistance. One is the friction from the pipe slowing the water down, and the other is the size of the pipe itself. If the pipe is too small, only a limited amount of water can flow through. In a circuit, the resistivity of the materials is like the friction inside the pipe. The length of the wires connecting the devices is kind of like the width of the pipe.

So we have Ohm's Law at
The electrical potential of a circuit is equal to the flow of charge each second multiplied by the resistance to that charge. A concept to be thought about, rather than a bunch of letters.

With all the equations being thrust upon you at school, it's not hard to see them as just letters and numbers to be memorized and later forgotten. If you look at a formula and break it down into its units, and try to voice out what the formula implies, you can really grasp what's going on and learn a lot.


  1. doing that stuff in college, fuckin' hate it >.<

  2. yeah, it's rough to get through all the terminology and stuff.

  3. this is relevant to just what I was thinking about

  4. Good to know sometimes, I remember learning this in High School, oh brings me back lol.

  5. I failed grade 10 science, just sayin'

  6. FML i remember this from school and i HATED it.

  7. bring back good and bad memories :P

  8. Studying similar stuff in school.

  9. A huge wave of nostalgia just hit me. Haha. Thanks. :D

  10. nice drawing. helps me to understand. thanks. :)

  11. this brings me back to the days of high school