Experiment: Red Shift & Hubble’s Law
Part 1
Question:
What will happen to the wavelength of a wave drawn on a balloon when the balloon is
inflated?
Hypothesis:
[Include a reason]
Procedure:
1. Draw two dots on a balloon.
2. Draw a wave between them.
3. Measure the wavelength of the wave.
4. Inflate the balloon and measure the wavelength again.
Data:
Wavelength (cm)
Before Inflation
After Inflation
[Draw BEFORE and AFTER sketches]
Part 2
Question
What will happen to the distances between points drawn on an elastic when the elastic is
stretched?
Hypothesis:
[Include a reason]
Procedure:
1. Draw five circles (galaxies) on a piece of elastic, approximately equidistant from each other.
2. Choose a ‘home galaxy’.
3. Measure the distance from the ‘home galaxy’ to each of the others.
4. Stretch the elastic and measure the distances again.
Data:
Distance ‘home’ to 1 Distance ‘home’ to 2 Distance ‘home’ to 3 Distance ‘home’ to 4
Before stretching
After stretching
[Draw BEFORE and AFTER sketches]
Conclusions [copy & answer]:
1.
In Part 1, what happens to the distance between any two points as the balloon expands?
2.
Did the wavelength of the wave increase, decrease or stay the same?
3.
What caused the change in wavelength?
4.
Hubble used a spectrograph to observe similar changes in the wavelength of light coming from other
galaxies:
- how did he explain that this light was 'redder' than expected?
- what conclusion did he make about the current state of the universe?
5.
In Part 2, which of the following is true?
a)
c)
d)
the closer together two circles were in the beginning, the more they moved away from each other when
the elastic was stretched.
the farther apart two circles were in the beginning, the more they moved away from each other when the
elastic was stretched
the circles all moved away from each other by the same amount.
the circles did not move.
6.
How does question 5 and its answer apply to the universe and the galaxies?
b)