Working principle
A flyback converter transforms a DC voltage at the input to a DC voltage at the output. The operating principle is similar to the buck-boost converter, but an additional transformer is used to achieve galvanic isolation of the input and output.
For a flyback converter in continuous conduction mode the output voltage across resistor R is given by:

where D is the duty cycle, and N1 and N2 are the turns numbers of the primary and secondary windings.
Experiments
Change the winding ratio from 1:1 to 0.5:1 and observe how the output voltage increases by a factor of 2.