Hi, I have a question concerning a hydrogen spectrum: There are 4 energy levels drawn: Starting from the top -1.4 * 10^-19 Joules -2.4 * 10^-19 Joules -5.4 * 10^-19 Joules -21.8 * 10^19 Joules 1st question: Going from the second level to the third from the top (from -2.4 to -5.4) gives rise to a red line int he hydrgen emission spectrum. Calculate the wavelength. I have done this, and found it to be 6.63 * 10-7 metres 2nd Question: This is where I am confounded! Draw two arrows on the diagram labelled IR and the ther UK, to show the transitions giving rise to lines in the infrared and ultraviolet regions. Explain how you made your choice for both... I know that Infrared usually has a wavelength of 10^-5 metres, and UV has 10^-8 metres. From this, I tried to find what transition is required: E2-E1 = Planck's COnstant * Frequency (Velocity/Wavelength). But I do not think this is correct. HELP ANYBODY! Thank You.