Question

As a distant star moves away from earth, the light given off by the star has a

Answer 1

Answer:

The wavelength of these photons will become longer. The energy of each of these photons will become lower.

Explanation:

Wavelength

Light can be considered as electromagnetic waves. The wavelength of a wave is equal to the minimum distance between two troughs (lowest points) in this wave. On the other hand, the frequency of a wave is equal to the number of wavelengths that this wave travels in unit time.

Assume that the speed of light stays the same. The distance that this beam of light travels in unit time will be the same. However, with a lower frequency, there would be fewer wavelengths in that same distance. Therefore, the size of each wavelength will become longer.

If $c$ represent the speed of light and $f$ represents the frequency, then the wavelength would be:

$\displaystyle \lambda = \frac{c}{f}$.

Energy

The energy $E$ of each proton of a beam of light is proportional to the frequency $f$ of the light. Let $h$ denote Planck's Constant. The numerical relation between $E\!$ and $f\!$ would be:

$E = h\, f$.

Therefore, if the frequency $f$ of this light becomes smaller, the energy $E$ of each of its proton will also become proportionally lower.