MS in Physics after Bachelors in Mechanical engineering I am in the final semester of my mechanical engineering bachelors, though I could have finished my bachelors about  4 months ago, but I failed to clear 2 of my subjects, for which I would appear again in the December examination. Physics has always caught my attention, but then, everything I see catches my attention.I want to study physics now after I get my degree. The problem is my grades. I have scored an aggregate of 65% in my bachelors, but I can learn and understand things once I decide to do so. I am from India. How can I apply in foreign universities for MS, considering that they take engineering graduates for MS in physics, what kind of entrance/competitive exams would I have to give.
Thanks.
Changing fields from Engineering to Physics should not be a problem. I have several colleagues who have done this at various universities. Although, you would need to check with the specific universities you are interested in. If you are applying to universities in the United States you will likely need to take the GRE exam (some non-US universities will also consider GRE exam scores in the application process). As you are applying from India you may also need to take the TOEFL test. 

Your grades may hold you back since most high-ranked universities require an average over 75% for graduate studies. These are the University of Toronto minimum entrance grade equivalents from Indian universities:


  Bachelor's Degree Equivalent: Completion of BOTH a Bachelor's
  (three-year) degree and a Master's OR A Bachelor's degree requiring
  four years of study (e.g. BPharm, MBBS, BDS, BTech, BEng, or BArch)
  
  Mid-B Equivalent: 1st Class or 1st Div.; 7.5/10 from Indian Institutes
  of Technology; 8.0/10 from other institutions


However, good exam scores, relevant research experience, and good reference letters may help make up for the difference. It is worth discussing with a potential supervisor at your intended university who may be willing to support your application, as this can often help.