Ohm's Law
Applying Ohm's Law-Regardless of which alloy is selected, all electrical resistance type heating elements will operate on either alternating or direct current according to the ratio between the alloy's resistance (ohms), the applied electromotive force (volts), and the current (amperes). This ratio, called Ohm's Law, may be expressed by the equations given below.
In as much as the electrical resistivity of all heating element alloys will increase somewhat with temperature, the ohmage as calculated by the above formulae should be considered the "hot resistance" necessary for a given wattage in a device when it is at operating temperature. While the average percent increase in resistance for each of the ChromelŽ alloys is given on preceding pages, it is recommended that a test be made on a finished prototype device to determine the proper allowance to make for this increase in resistance.
| Volts = Amperes X Ohms | E = I X R |
| Amperes = Volts ÷ Ohms | l = E ÷ R |
| Ohms = Volts ÷ Amperes | R = E ÷ l |
| Watts = Volts X Amperes | W = E X l |
| Watts = (Volts)˛ ÷ Ohms | W = E˛ ÷ R |
| Watts = (Amperes)˛ X Ohms | W = I˛ X R |
| Ohms = Watts ÷ (Amperes)˛ | R = W ÷ I˛ |