Hey aspirant,

after doing your 12th grade with physics, chemistry and biology you can apply for a Bachelor degree in psychology be it a B.A. or a B.Sc. course. About Bachelor of Arts (BA) Psychology: BA in psychology is an undergraduate level programme which goes on for a duration of three years.

• Finish a related bachelor's degree program. ...
• Enroll in a graduate program. ...
• Complete an internship or practicum. ...
• Apply for a license. ...
• Get board-certified. ...
• Apply for child psychologist jobs.

Hope that answers.  All the best!