blueshift is observed when
a) a distant luminous object travels rapidly towards an observer
b) a luminous object is stationary to an observer
c) a distant luminous object travels rapidly away from an observer
d) a luminous object travels alongside an observer
c) a distant luminous object travels rapidly away from an observer
c) a distant luminous object travels rapidly away from an observer
The correct answer is option c) a distant luminous object travels rapidly away from an observer.
Blueshift refers to a phenomenon in which light waves appear to be shifted towards shorter wavelengths, resulting in a shift towards the blue end of the spectrum. This phenomenon occurs because light waves get compressed or "squeezed" when the source of light moves rapidly away from an observer.
To understand this concept, we can use the Doppler effect. The Doppler effect is the change in frequency or wavelength of a wave as perceived by an observer moving relative to the wave source. In the case of light, a similar effect occurs when a light source moves relative to an observer.
When a luminous object is stationary or travels alongside an observer (options b and d), there is no relative motion between the object and the observer, so there would be no observable shift in the light's wavelength. Thus, blueshift is not observed in these scenarios.
On the other hand, when a distant luminous object travels rapidly towards an observer (option a), the light waves get compressed or "squeezed" due to the relative motion. This compression causes a shift towards shorter wavelengths, resulting in a blueshift.
Finally, when a distant luminous object travels rapidly away from an observer (option c), the light waves get stretched because of the relative motion. This stretching causes a shift towards longer wavelengths, known as redshift. Therefore, blueshift is observed when a distant luminous object travels rapidly away from an observer.