Physics does not have its own International Master's Degree programme in University of Oulu, which means that you can only apply to the same Master's (Or Bachelors+Master's) Degree programme as Finnish students through www.studyinfo.fi. The application period for Master's is in January, and the period for Bachelor+Master's is in March-May.
2017 application periods:
The Finnish programmes do not ensure you teaching or service in English (especially at Bachelor level). You also have to pass a "maturity exam" during the studies, which tests your proficiency in Finnish or Swedish. In practice however, many courses are taught or can be completed in English.
Last updated: 10.2.2017