HyperPhysics - Voltage
Engineering LibreTexts - Energy and Voltage
Engineering LibreTexts - Energy and Voltage
Wonderful tutorial go get a common-sense grasp of voltage.
Physics LibreTexts - Electromotive ForceDetailed well-illustrated tutorial that conveys the distinction between EMF and terminal voltage. Don't get lost in the weeds. The MCAT tends isn't usually too difficult about this stuff.
DC Current Resources
20 questions
concept review with practice items
figures for classroom presentation