Electric potential differnce is defined as:
[tex]\Delta V=\int_{a}^{b}E\cdot dl[/tex]
If we asume the electric field is constant we get:
[tex]\Delta V=\int_{a}^{b}E\cdot dl=E\Delta L[/tex]
We need to calculate the electic field strenght:
[tex]F=qE\\
[/tex]
[tex]E= F/q\\
E=\frac{25\cdot 10^{-6}}{50 \cdot 10^{-6}}=0.5 \frac{V}{m}[/tex]
We can now calculate the potential difference:
[tex]\Delta V=E\Delta L=0.5 \frac{V}{m}\cdot15m=7.5V[/tex]
