Here are some simple graphical illustrations provided by Cohen in "The Bible of Options Strategies", publsihed 2005 by FT Prentice Hall.
A long call (page 7) mostly shows positive Rho values (indicating that "higher interest rates would increase the value of the calls and therefore help the position; whereas a synthetic call (page 248) mostly shows negative Rho values (indicating that "higher interest rates are generally unhelpful to the position").
A long put (page 15) mostly shows negative Rho values; whereas a synthetic put (page 252) mostly shows positive Rho values.
A long call (page 7) mostly shows positive Rho values (indicating that "higher interest rates would increase the value of the calls and therefore help the position; whereas a synthetic call (page 248) mostly shows negative Rho values (indicating that "higher interest rates are generally unhelpful to the position").
A long put (page 15) mostly shows negative Rho values; whereas a synthetic put (page 252) mostly shows positive Rho values.


