Which expression correctly represents Ohm's law using E for voltage, I for current, and R for resistance?

Which expression correctly represents Ohm's law using E for voltage, I for current, and R for resistance?

• A. E = V / R
• B. E = I / R
• C. E = I R
• D. E = R - I

Answer: (C)

The expression for Ohm's law with E for voltage, I for current, and R for resistance is E = I × R. This captures the direct proportionality between voltage and the product of current and resistance: if you know the current through a resistor and its resistance, multiplying them gives the voltage across it. Units check out too: amperes times ohms equals volts (A × Ω = V). For example, with I = 2 A and R = 5 Ω, E = 10 V. The other forms don’t fit: E = V/R would mix up units to amperes; E = I/R gives units of siemens, not volts; and E = R − I combines unlike quantities.

The expression for Ohm's law with E for voltage, I for current, and R for resistance is E = I × R. This captures the direct proportionality between voltage and the product of current and resistance: if you know the current through a resistor and its resistance, multiplying them gives the voltage across it. Units check out too: amperes times ohms equals volts (A × Ω = V). For example, with I = 2 A and R = 5 Ω, E = 10 V. The other forms don’t fit: E = V/R would mix up units to amperes; E = I/R gives units of siemens, not volts; and E = R − I combines unlike quantities.