Given resistance, R = 12.5

Given resistance, $R = 12.5 \, \Omega$
Given current, $I = 10 \, \text{A}$
Ohm's Law states that potential difference ($V$) is the product of current ($I$) and resistance ($R$):

$$V = IR$$

$$V = 125 \, \text{V}$$

The potential difference across the resistor is $\text{125 V}$.