4. Suppose the following values for a given emission line were obtained with a meter stick spectroscope: a = 17.00 cm b = 40.00 cm rulings/mm of grating = 600 mm- Calculate and then , in m and nm units. Assume that a first-order spectrum was observed. Note that the lines per mm of grating must be converted to mm per ruling. Your result should be in the visible portion of the electromagnetic spectrum. If it is not, check your units. If you set up an Excel spreadsheet to calculate these values, you will be able to use it to analyze your data from the experiment.