Basics of Electricity

Units of Electricity

 The most basic units in electricity are:

• Voltage (V): Measured in volts, voltage relates to the pressure of electric flow.
• Current (I): Measured in amps, current can be viewed as the amount of electricity flow
• Resistance (R): Measured in ohms, resistance, as the term implies, addresses the amount of constraint on the flow of electricity

These units are related, as illustrated by the following equation, referred to as “Ohm’s Law”:

V = I x R

Applying this equation, one can see that an increase in voltage without an increase in resistance must, by definition, cause an increase in current. Similarly, given no change in voltage on a circuit, a decrease in resistance must be acoompanied with an increase in current flow.

The other commonly used measure of electricity is power (P), measured in watts, is expressed as a relationship between voltage and current:

P = V x I

As represented by the above formula, electrical power can be increased in two ways:

• Increasing the voltage (pressure of current flow)
• Increasing the current (amount of electricity flow)

Electrical Efficiency

In applying the above units of electricity and their interrelationships, one can find a key to improving the efficiency of electricity. Consider 2 scenarios:

• Secenario 1: A 6-volt light bulb tied to a 6-volt battery with a power output of the light bulb of 100 watts. Using the above formulae, 16.66 amps of current would be required to fully power up this 6-volt light bulb.
• Scenario 2:  A 12-volt light bulb tied to 12-volt battery with a power output of of the light bulb of 100 watts. Using the above formulae, 8.33 amps of current would be required to fully power up this 6-volt light bulb.

So, by doubling the amount of voltage (pressure of electricity flow), it takes half the current to generate the same amount of power. This obvious efficency-related advantage is even more significant when one realizes that the resistance inherent in electrical wires consumes power, and that as current increases so does the amount of power consumed.

Combining the above described formulae, one can see the relationship between power, current and resistance:

P = I² x R

Thus, wires that are smaller or of less conductive material will consume more power, but the impact of increase in current is even more dramatic. So, by increasing the voltage and reducing the current necessary to power a system significantly improves electrical efficiency.