I am studying the electric potential energy and for the first time i red about the electric potential. The book Halliday et al. states that the electric potential can be defined as V = U/q where q is the test charge in the electric field, so the first question is: can the electric potential V be negative? In which cases this happens?
The second question is related to the electronvolt. The book states the electronvolt is the energy gained by an elementary charge, such as a proton or electron, to pass through a potential difference of 1 V. It says also that the eV can be obtained by the following formula: ΔV*q = -L where q is the test charge in the electric field and L is the work done on the test charge by the electric field. Now I tried to calculate the electronvolt for the electron and the proton but i am not sure if it is correct.