Time management is very much important in IIT JAM. The eduncle test series for IIT JAM Mathematical Statistics helped me a lot in this portion. I am very thankful to the test series I bought from eduncle.
Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Ruby negi
https://www.google.com/url?sa=t&source=web&rct=j&url=https://amp.doubtnut.com/question-answer-physics/a-ring-of-mass-m-and-radius-r-is-rotated-in-uniform-magnetic-field-b-which-is-perpendicular-to-the-p-33101538&ved=2ahUKEwiJwYPXm63tAhUvgtgFHb_nDgQQFjAAegQIARAB&usg=AOvVaw3rFof1UkhvIL2aXci1-A_v&cf=1
see this..