a. A laser light is described as producing light that is both highly coherent and highly monochromatic. Explain what is meant by the terms coherent and monochromatic.

b. This diagram shows the experimental setup (left) used to analyse the spectrum of a sodium discharge lamp with a diffraction grating with 500 lines mm⁻¹, and the spectral lines observed (right) in the developed photographic film.

i. Explain why two spectra are observed.
ii. Describe two differences between these two spectra.
iii. The green maximum near end A is at an angle θ of 19.5°.
Calculate the wavelength of the green light.
iv. Calculate the angle produced by the second green line.

Transcribed Image Text:

collimator diffraction grating ff A violet blue green yellow red violet blue green yellow red sodium lamp photographic film Figure 13.30