The mathematical formula is written in one of the following three ways:

a. E = I x R. The voltage in a circuit equals the current multiplied

by the resistance. An example of Ohm's Law in relation to voltage is an

electric heater which has a known resistance of 20 ohms. The same heater

requires a current flow of 6 amperes for proper operation.

Figure 13. Determine Voltage.

b. I = E/R. The current equals the voltage divided by the resistance.

An example of Ohm's Law in relation to current is an electric horn that

requires a pressure of 12 volts and offers 3 ohms of resistance to the flow of

current.

Figure 14. Determine Current.

c. R = E/I. The resistance of the circuit equals the voltage divided by

the current. An example of Ohm's Law in relation to the resistance is an

electric iron that operates from a 120 volt input and requires a current flow

of 5 amperes.

Figure 15. Determine Resistance.

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