AP Physics C: Electricity and Magnetism / Unit 9: Electric Potential
9.2 Electric Potential
Notes
$$V=\frac{kq}{r},\qquad \Delta V=-\int\vec E\cdot d\vec l,\qquad E_x=-\frac{dV}{dx}$$
- Potential is a scalar: add potentials from several charges directly.
Practice
$V(x)=5x^2$ V. $E_x$ at $x=2$ m:
$\displaystyle -\frac{dV}{dx}=-10x$.
At the midpoint of $+q$ and $-q$, the potential:
Equal and opposite.
The field points toward:
$E=-\nabla V$.
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