Which expression represents the formula to solve for voltage in Ohm's law?

• A. E = I * R
• B. E = I + R
• C. E = V / I
• D. E = IR

Answer: (D)

Ohm's law shows voltage is the product of current and resistance. When solving for voltage, you isolate that variable, giving voltage equals current times resistance. If the symbol for voltage is E, that becomes E = I × R, written as E = IR. This form fits the units as well: amperes times ohms gives volts. The other expressions don’t directly represent voltage from current and resistance or mix in the wrong operations, so the form E = IR is the correct way to express voltage in this context.