Final answer:
In a series circuit, the resistor with the highest resistance value will have the largest potential difference across it. Therefore, in a series circuit with 2 Ω, 5 Ω, and 15 Ω resistors, the 15 Ω resistor will have the largest potential difference.
Step-by-step explanation:
In a series circuit, the same current flows through all resistors, as they are connected one after another. The potential difference or voltage drop across each resistor in the series is directly proportional to its resistance, according to Ohm's Law (V = I x R), where V is the voltage, I is the current, and R is the resistance.
Given the resistors with resistance values of 2 Ω, 5 Ω, and 15 Ω connected in series, the resistor with the largest resistance, which in this case is the 15 Ω resistor, will have the largest potential difference across it. This is because the current flowing through the circuit is constant for all components, hence the resistor with the highest resistance will have the highest voltage drop.