Hello, I would like to ask a few questions regarding funding in grad school for physics (and maybe for other fields). I know that tuition fees are quite large in grad school, but most of the time (if not always) they are being covered by the school. People who receive funding from school has to do duties like TA, RA including grading papers and so on. My main question is: can graduate student live (pay for rent, buy food) only using money received from the university due to their duties and without having external source of income? I am primarily interested in physics, but it would be nice to know about non-science fields too.