How VGT(VARIABLE GEOMETRY TURBO) WORKS??READ DESCRIPTION PLEASE

hello everyone, sorry for a little mistake in video,JO A/R Ka ratio hai usme R maine bataya hai radius of turbine wheel,but R actually mei wo radius hai jo turbo ke center se turbine housing k centroid tak hai jaisa ki photo mei dikha bhi raha hai,so please sorry but i hope aapko clear ho jaayega sab,. and baaki enjoy the video, thank you