hey,

i hope you are doing well , yes you are eligible to do B.tech after completing your B.Sc physics you just need to fulfill the eligibility criteria of the colleges you are planning to take admission in, moreover BS.c graduates are eligible for the lateral entry in engineering you can take admission from that .

the condition is that you must have secured a minimum aggregate of 50 percent marks in your graduation and you necessarily have studied mathematics subject in your graduation

i hope this helps

good luck!