Question

Suppose you are an astronomer, and a child asks you to explain the light given off by stars. In your own words, describe the relationship between the energy, frequency, and wavelength. Be sure to include information about the electromagnetic spectrum in your discussion.

Answer 1

The energy, frequency and wavelength of emitted radiations from stars are related as - $E = hf =\frac{hc}{\lambda}$

EXPLANATION :

Before answering this question, first we have to understand the Planck's quantum theory.

As per Planck's quantum theory, the energy of the emitted radiation is will be equal to the product of Planck's constant with the frequency of the emitted radiation.

Mathematically energy E = hf

Here, h is the Planck's constant and f is the frequency of emitted radiation.

We know that the wavelength is inversely proportional to frequency, and it is calculated as-

                      Wavelength  $\lambda=\frac{c}{f}$

Putting these values, we get energy E = $\frac{hc}{\lambda}$

Here, c is the velocity of light.

This formula is used for calculating the energy of radiations coming from stars.

Stars emit different radiations which have different frequencies like gamma ray, U.V ray and visible light.

From the electromagnetic spectrum, we know that more is the frequency of radiation, the more is the energy of the radiation.

Cosmic wave has more energy as it has more frequency. Gamma ray is followed by the cosmic wave which has the second most energy in the electromagnetic spectrum.

                     

Answer 2

Well, i would tell the kid that light is electromagnetic radiation which is visible. The frequency and wavelength is just right so the radiation becomes visible, and that visible radiation goes away from the star and reaches earth It also depends on the age of the child and the comprehension level