Yes, you can apply for an M.Sc. in Physics even if you have completed a Bachelor's degree in a science subject other than Physics. Many universities and institutions offer M.Sc. programs in Physics that are specifically designed for students with a non-physics background. However, there are a few important factors to consider before applying.

Admission Requirements:
- Most M.Sc. programs in Physics have specific admission requirements, such as a minimum GPA, prerequisite courses, and standardized test scores (e.g., GRE Physics subject test).
- While having a Bachelor's degree in a related field such as Mathematics, Engineering, or Chemistry can be advantageous, some programs may also consider applicants from broader science backgrounds.

Prerequisite Courses:
- If you have a non-physics background, you may be required to complete certain prerequisite courses to build a solid foundation in physics before starting the M.Sc. program.
- These courses may cover topics such as classical mechanics, electromagnetism, quantum mechanics, thermodynamics, and mathematical methods in physics.
- It is important to check the specific prerequisite requirements of the program you are interested in.

Bridge Programs:
- Some universities offer bridge programs or foundation courses in physics for students with non-physics backgrounds.
- These programs provide an opportunity to complete the necessary prerequisites and ensure that all students have a similar level of knowledge before starting the M.Sc. program.

Statement of Purpose:
- In your application, you will typically be required to write a statement of purpose explaining your interest in pursuing an M.Sc. in Physics despite your non-physics background.
- This is your opportunity to showcase your enthusiasm for the subject, highlight any relevant coursework or research experience, and explain how your previous studies have prepared you for the M.Sc. program.

Recommendation Letters:
- Strong letters of recommendation from professors or professionals in the field can greatly enhance your application.
- These letters should highlight your academic abilities, research potential, and potential for success in the M.Sc. program.

Conclusion:
In conclusion, it is possible to apply for an M.Sc. in Physics with a Bachelor's degree in a science subject other than Physics. However, it is important to carefully review the admission requirements, consider completing prerequisite courses if necessary, and highlight your passion for physics in your application materials.