## Electronics Reference

# DC Circuits

Multiplier | Prefix | Symbol | Multiplier | Prefix | Symbol |

exa | atto | ||||

peta | femto | ||||

tera | pico | ||||

giga | nano | ||||

mega | micro | ||||

kilo | milli | ||||

hecto | centi | ||||

deka | deci |

In 1826 Georg Simon Ohm discovered the relationship between voltage, current, and resistance, which is now known as Ohm’s law. Ohm’s law is the basic foundation for all circuit analysis and it states that the amount of current (I) is directly proportional to the voltage (V), and inversely proportional to the resistance (R).

The unit of electric power, watt (W), is named after James Watt. One watt of electric power is equivalent to the work done by a one volt potential difference in moving one coulomb of charge in one second. Since one coulomb per second is one ampere, we can also say that electric power is equal to volts times amperes as you can see in the equation.

When paying bills to electric utility companies, we are actually paying for the energy consumed over a certain period of time. To calculate the energy consumed, you can use this equation where,

P - Electrical Power (Watts, W)

t - time (seconds, s)