Which expression gives current in terms of voltage and resistance?

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

Answer: (D)

Current through a component relates to the voltage across it and its resistance in a simple way: more voltage pushes more current, but more resistance pushes less current. The expression I = V / R captures this directly: current equals voltage divided by resistance. If you double the voltage while keeping resistance the same, the current doubles; if you double the resistance with the same voltage, the current halves. A quick unit check confirms it too: volts divided by ohms gives amperes, since 1 V / 1 Ω equals 1 A. The other forms don’t fit the relationship: multiplying voltage by resistance would imply current grows with resistance and yields the wrong units; subtracting resistance from voltage mixes different quantities; and reversing the division to R / V would give units of ohm per volt and imply current that increases with resistance, which isn’t correct.