Khan Academy
Khan Academy: Calculus: Path Independence for Line Integrals
Video lesson introducing conservative vector fields and the multivariable chain rule. Shows that a vector field is conservative if the line integral is the same for the same starting and ending point regardless of the path taken. [17:14]
Khan Academy
Khan Academy: Path Independence for Line Integrals
This video shows that if a vector field is the gradient of a scalar field, then its line integral is path independent.