Question

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

measurably lower frequency. What happens to the wavelength and the energy
of the photons of light when the frequency becomes lower?

Answer 1

When a distant star moves away from Earth, the frequency of the light it emits decreases, causing a redshift in the wavelength. This results in a decrease in the energy of the photons of light.

Step-by-step explanation:

When a distant star moves away from Earth, the light it emits has a lower frequency, which means that the wavelength of the light becomes longer. As the wavelength increases, the energy of the photons of light decreases. This is known as redshift and is a result of the Doppler effect.

For example, if a star emits blue light with a short wavelength, as it moves away from us, the wavelength of the light will shift towards the red end of the spectrum. This is because the motion of the star causes the waves to compress, resulting in a longer wavelength and lower frequency.

It is important to note that even though the frequency decreases and the energy of the photons decreases, the total amount of energy emitted by the star remains the same.

Answer 2

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

Step-by-step 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 = (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.