In a hydrogen atom only 1s orbital is filled. Does this mean that the energies of all other orbitals are equal? If so,why?
Sure, if they are unoccupied they contribute nothing to the total energy of the system. Remember that orbitals are mathematical constructs and only have meaning with regard to their energy when being physically occupied by an electron that adheres this mathematical description. The energy required to fill such an orbital however differs (vastly) from orbital to orbital and nucleus to nucleus (see for example http://www.colby.edu/chemistry/PChem/notes/AOIE.pdf).