Ford Electrical Training Practice Test

When resistance increases in a circuit, heat production also increases due to the relationship described by Joule's Law, which states that the heat generated (H) is proportional to the square of the current (I) and the resistance (R). This relationship can be represented with the formula H = I²R.

As resistance rises, for a given amount of current flowing through the circuit, the amount of heat generated increases since you are multiplying a larger resistance value by the square of the current. Consequently, if the circuit has a constant voltage, the current may decrease as resistance increases, but the effect of increased resistance tends to lead to greater heat generation overall. This principle is crucial for understanding how resistive loads, like heaters or incandescent bulbs, operate in electrical systems, as their efficacy is largely tied to the heat that they produce through resistance.