Question

Two stars ${{P}}$ and ${{Q}}$ are observed at night. Star ${{P}}$ appears reddish while the star ${{Q}}$ as white. From this, we conclude:
A) Temperature of ${{Q}}$ is higher than that of ${{P}}$
B) Temperature of ${{Q}}$ is lower than that of ${{P}}$
C) Star ${{Q}}$ is at the same distance as that of star ${{P}}$
D) Star ${{P}}$ is farther away than star ${{Q}}$

Answer 1

Each color has a different wavelength. For example, the red color has the longest wavelength and the violet color has the shortest one. When all the colors with different wavelengths mix up they make white light. If an object reflects this white light that means that it has not absorbed light of any wavelength.

Complete step by step solution:
When the light waves are absorbed by an object, the energy from the light waves is transferred from the light waves to the object. This increases the internal energy of the plane. When white light is incident on any object, there are three possibilities, first that the object absorbs the complete light, or the object completely reflects the white light and the last possibility is that it absorbs a part of the light and reflects the rest of it.
Therefore, if the star ${{Q}}$ appears white then it should have reflected all the light incident on it, while the star ${{P}}$ appears reddish because it would have observed waves of some particular waves and reflected the rest of it due to which it appears of a particular color and the temperature of the star increases. The distance of the star will not affect the light which we see when it is reflected from the stars.

The correct answer is (B), Temperature of ${{Q}}$ is lower than that of ${{P}}$.

Note: If an object reflects a particular wavelength of light then it must have absorbed the rest of the light. Therefore, if the object absorbs some light then its energy would increase which would increase the temperature of the object.