Then they asked him to write down the Maxwell's equations. Mahbub bhai wrote is down with exterior derivatives in one line (most useful and elegant form for theoretical physicists). The interviewers did not understand what he wrote and asked him to write it again. Mahbub bhai now wrote it with tensor notation. The interviewers again found it incomprehensible and asked for it again. At some point Mahbub bhai wrote all four Maxwell equations in a form understandable for first year physics students and everybody was happy.