Question

The colour of a star indicates its:

• A. temperature
• B. distance
• C. velocity
• D. size

Answer 1

Answer: (A)

According to weins displacement law ${\lambda }_{m}T=$ constant or temperature $\propto \frac{1}{{\lambda }_n}$ It represents that greater the temperature T of an emitted star, smaller the value of wave length $\lambda$. We also know the wave length of ray depends upon its colour. Hence, when the temperature of star increases, the wave length of star decreases. When temperature of star decreases, the wave length increases and star moves towards the red colour. Therefore, the colour of star indicates its temperature.