Here, a model of Nipkov’s disc scanner is installed. Rotate the handle and observe the holes made on the surface of the disc. When the disc is rotated, see through the view finder.

What did you observe? 
You can visualize the picture drawn beyond the disc.

The science behind it :
As the disc consists of small holes, each hole traverse every point of the picture behind it while rotating. Hence we are able to view the entire picture.