for half wave rectifier for 1 half of the input cycle the transformer secondary is unused .but for centre tap full wave rectifier for both halves 1 half of the 2ndary is used. for the bridge rectifier however the entire 2ndary is used for both the halves . so T.U.F of half wave < full wave < bridge rectifier . am i correct ? but i think TUF of primary winding in all the 3 cases should be same .is it ?