Umm depends. AP doesn't give you extra credits per semester/marking period, however if it is longer than the standard class than you'll get more credits. at my school:
Economics = .5 credits (1 marking Period)
International Relations= .5 Credits (1 marking Period)
AP Macroeconomics = 1 Credit (2 marking periods)
AP Comparative Government = 1 Credit (2 Marking periods)
English
AP English = 1 credit (2 marking periods)
English = 1 credit (2 marking periods)
Math is the same way as Social Studies
AP Statistics = 1 credit (2 marking periods)
Statistics = .5 credits (1 marking period)