University Mathematics Handbook (2015)
IX. Vector Analysis
Chapter 11. Conservative Field in General
a. Vector field is called conservative field if there exists scalar field such that .
b. Vector field of class above simply connected surface body (that is, on every closed curve or there exists a two-sided surface, of which is its boundary) is conservative if, and only if, one of the following propositions hold:
1. for every simple closed line in .
2. Integral is independent of the line connecting points and , which is entirely in .
3. There exists scalar field holding . In other words, the expression is a full differential. It means there exists a function such that and there holds .
4. .
c. If filed is conservative in and is a point in , then the potential function can be calculated using one of the following formulas: