1. The problem statement, all variables and given/known data Use the law of electromagnetic induction to deduce what typical voltage would be imposed in the magnetopause by the interplanetary magnetic field, assuming a scale size of the magnetopause of 10Re? 2. Relevant equations -Magnetic flux equation -Faraday's law 3. The attempt at a solution See attachment for solution. I took the interplanetary magnetic field strength to be 10^-9T (is this right?) and assumed that the magnetopause rotates at the same rate as the Earth. Did I get it right? I normally do this sort of calculation for conductors rotating in a magnetic field. In this case one magnetic field is imposing an emf on another magnetic field. Did I have to take into account the strength of the magnetopause? Thanks a lot for any advice.