A voltage drop is best described as the decrease in voltage across a component in a circuit.

• A. The total supply voltage in the circuit
• B. The voltage across the source before any load
• C. The sum of all voltage rises around a loop
• D. The decrease in voltage across a component due to resistance

Answer: (D)

Voltage drop is the decrease in electric potential that occurs as current passes through a specific component. In a resistor, this drop is described by V = I · R—the potential difference from the input side to the output side that represents energy per unit charge being dissipated as heat. So, the drop across a single component reflects how much voltage is used up by that element as current flows through it.

The other ideas describe different things: the total supply voltage is the overall driving potential for the whole loop, the voltage across the source before any load is just the source’s own potential, and the sum of voltage rises around a loop is a statement from Kirchhoff’s voltage law about the balance of rises and drops in a loop. What defines a voltage drop is the local decrease across that one component, often tied to its resistance (or impedance).