What formula is used to calculate resistance in a circuit?

Ohm's Law defines the relationship between voltage (E), current (I), and resistance (R). The foundational formula is E = I x R. To solve for resistance (R), you must divide both sides of the equation by current (I), which results in the formula R = E / I. Distractors like R = E x I are incorrect because multiplying voltage and current actually calculates electrical power (Watts), not resistance. The options featuring addition and subtraction (E + I, E - I) are mathematically invalid in this context because you cannot directly add or subtract units of different fundamental types like volts and amps.