Question

the diagram below shows the spectral lines for an element.
violet red
diagram of spectral lines
which diagram best represents the spectral lines of this element when its light is observed coming from a star that is moving away from earth?

1. violet red

diagram 1

1. violet red

diagram 2

1. violet red

diagram 3

1. violet red

diagram 4

Explanation:

Step1: Recall Doppler Effect in Light

When a light source (like a star) moves away from an observer (Earth), the light waves are stretched, causing a redshift. This means spectral lines shift towards the red (longer wavelength) end of the spectrum.

Step2: Analyze the Original and Option Diagrams

• Original diagram: Spectral lines are in a certain position between violet and red.
• For a star moving away, spectral lines should shift towards red. So we check which diagram has lines shifted right (towards red) compared to the original.
• Diagram 2: The spectral lines are shifted towards the red end (right side) relative to the original. Other diagrams either don't shift (Diagram 1), shift left (Diagram 3,4) or have different patterns.

Answer:

Diagram 2 (the second diagram showing spectral lines shifted towards the Red end)