M.Sc

M.Sc in Mathematics graduates can find lot of opportunities in Research and Development firms, Economic Research firms, Market Research firms and Manufacturing firms. They can look for the job profiles like Quantitative Risk Analyst, Statistician, Treasury Management Specialist and Demographer in these firms. Those who want to work in public sector can find ample opportunities in various government organizations like Defense Research and Development Organization (DRDO) and Indian Space Research Organization (ISRO). Reputed Software companies offer several career opportunities for these graduates in operation research, software design and programming. Banks and Insurance companies also offer lucrative opportunities for the candidates who have completed their postgraduate degree in Mathematics. They can also work in various government colleges after qualifying SET or NET exam.

Hello Govind,
Yes, you can. Most universities require you to have physics as your extra-departmental/pass course for you to study physics in M.Sc. However, since science departments offer admission to Master's degree students via entrance exams, this might be difficult anyway. You'll have to work hard in physics to crack entrance exams. Alternatively, you could apply for an applied mathematics degree in Calcutta University or CMI or even for M.Sc in mathematics. Most of the departments have someone or the other working in the mathematical physics. Courses that are relevant to that are differential geometry, probability theory/functional analysis, representation theory/Lie groups and of course, the theory of differential equations.
Approaching physics via mathematics is reasonably common.