Question

You view a visible light spectrum from an unknown object. You see many thin lines of color on a black background. What sort of spectrum is this and what does it tell you?

a) Emission spectrum, indicating a hot, dense object
b) Absorption spectrum, indicating a cooler object in front of a hot background
c) Continuous spectrum, indicating a solid object
d) Blackbody spectrum, indicating a perfect radiator

Answer 1

The spectrum described is an emission spectrum, characterized by bright lines against a black background, indicating light emitted by an excited gas that reveals the elements present.

Step-by-step explanation:

The visible light spectrum you are describing, with many thin lines of color on a black background, corresponds to an emission spectrum. An emission spectrum appears as a series of bright lines and it indicates that you are observing light emitted by a gas in which only certain discrete wavelengths are present.

This occurs when a gas is excited, for example, by an electrical discharge, and then emits light at specific wavelengths which can be seen when the light is passed through a prism.

The pattern of these bright lines is unique to each element, and by analyzing them, we can learn what elements are present in the glowing gas. This is distinct from an absorption spectrum, which is observed when a cooler gas absorbs certain wavelengths of light from a continuous spectrum, leaving dark lines. Therefore, the correct answer to the question is (a) Emission spectrum, indicating a hot, dense object.