1. The problem statement, all variables and given/known data https://postimg.org/image/6dbwajk91/ (Image inserted by moderator to make it visible in-post) In the circuit the switch is closed for several seconds, then opened. Make a graph with the abscissa time in milliseconds, showing the potential of point A with respect to ground, just before and then for 10 milliseconds after the opening of switch. Show also the variation of the potential at point B in the same period of time. 2. Relevant equations V=iR E=L*di/dt Kirchhoff's laws 3. The attempt at a solution So is there any potential larger than ground(V=0) on point A just after the switch is opened? In one way I think there should be some potential left since discontinuous change is unnatural. But I cannot clearly prove this. Also, the problems asks me to get the variation of potential B as time passes, but since point B is grounded, I cannot help thinking that potential of B is just 0 regardless of time. Am I wrong?