suppose we have a series of frames we want to find the motion vectors between two consecutive frames then then what should be the total number of motion vectors for a particular frame
It basically depends on your definition of the motion vector. Motion vectors can be calculated for each pixel of the image, then, the number of motion vector would be equal to the number of pixels in the frame. In most of the video coding, block based motion estimation is used, where the image is divided into number of blocks and for each block the motion is estimated. So the number of motion vector would be equal to the number of blocks in the frame.