Planck Length Question

[Ed Quanta]

[QUOTE=PhilthyPhil]The question I am trying to answer is:
'Explain why you would expect the Plank length to depend on the three fundamental constants G, c and h, ie assume that there is some function with f(lp,G,c,h)=0'

So..., what is the answer?

[selfAdjoint]

The Planck length is DEFINED to be a certain function of those constants, such that all their other dimensions cancel out, and one is left with only the dimension of length. Similar definitions with different formulas give Planck time and Planck mass.