Hello, I have no idea how to do the following question. Any help would be appreciated:

Question

An energy of at least 13.6 electron-volts is required to ionise a hydrogen atom. What is the longest wavelength of electromagnetic wave capable of ionising hydrogen? And which regions of the E-M spectrum correspond to photons capable of ionising hydrogen?

Answer 1

1) E=planck'sconstant*speedlight/wavelength
solve for wavelength.

2) http://www.astro.virginia.edu/class/oconnell/astr121/im/em-op-spectrum.gif