Question

In this experiment you used the hydrogen spectral lines to calibrate the spectroscope and, with this information, analyzed the helium emission spectrum. Based on your experimental data and the calibration, what is the wavelength of the most energetic photon emitted from helium in the visible region (expressed in nm)?

Answer 1

Visible region:
300 - 700 nm approx.
Helium spectral lines:

The most energetic photon emitted from helium will be the one with the smallest wavelenght.
Remember Planck´s equation:
E = hc/
(for a smaller wavelenght, the energy increases)

So, the wavelenght of the most energetic photon emitted from helium in the visible region is 388 nm.