Here is the step-by-step solution to the problems on the worksheet.
Step 1: Understand the Rules
Before answering the specific questions, let's look at the rules provided in the text and diagrams:
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Moving Toward Earth: Light waves get squashed (compressed). This shifts the spectrum toward the
Blue end (shorter wavelengths).
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Moving Away from Earth: Light waves get stretched out. This shifts the spectrum toward the
Red end (longer wavelengths).
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Speed: The faster the object moves, the bigger the shift (the further the lines move away from the dotted "stationary" lines).
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Step 2: Solve Question 1
Task: Use an arrow to indicate the direction that the spectrum would appear to shift if the object was moving toward you.
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Reasoning: When an object moves toward you, the light waves are compressed. As the diagram shows, compressed waves correspond to the "Blue" side of the spectrum (which has shorter wavelengths, around 400 nm).
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Action: You need to draw an arrow pointing to the
left, towards the blue/violet end of the scale.
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Step 3: Solve Question 2
We need to compare spectra A, B, C, and D against the stationary reference (the dotted lines).
a. Which of the spectra show an object that is moving toward you?
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Logic: Moving toward = Blue Shift. We are looking for spectral lines that have moved to the left (towards the 400 nm/blue side) compared to the dotted lines.
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Analysis:
* Spectrum A: Lines are shifted right (Red).
* Spectrum B: Lines are shifted left (Blue).
* Spectrum C: Lines are shifted right (Red).
* Spectrum D: Lines are shifted left (Blue).
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Result: Spectra
B and D.
b. Which of the spectra show an object that is moving away from you?
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Logic: Moving away = Red Shift. We are looking for spectral lines that have moved to the right (towards the 700 nm/red side) compared to the dotted lines.
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Analysis:
* Spectrum A: Lines are shifted right.
* Spectrum C: Lines are shifted right.
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Result: Spectra
A and C.
c. Which of the spectra show an object that is moving the fastest away from you?
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Logic: Faster speed = Larger shift. We compare the objects moving away (A and C). We need to see which one has its lines shifted further to the right.
*
Analysis:
* In Spectrum A, the lines have moved a moderate distance to the right.
* In Spectrum C, the lines have moved a very large distance to the right (they are much closer to the red edge than in A).
*
Result: Spectrum
C.
d. Which of the spectra show an object that is moving the fastest toward you?
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Logic: Faster speed = Larger shift. We compare the objects moving toward us (B and D). We need to see which one has its lines shifted further to the left.
*
Analysis:
* In Spectrum B, the lines have moved a small distance to the left.
* In Spectrum D, the lines have moved a very large distance to the left.
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Result: Spectrum
D.
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Final Answer
1. Draw an arrow pointing to the
left (towards the blue/400 nm end of the spectrum).
2.
a. B and D
b. A and C
c. C
d. D
Parent Tip: Review the logic above to help your child master the concept of the doppler effect worksheet.
