Question

Which color of light has the highest energy?
a).Violet
b).Green
c).Yellow
d).Orange
e).Red

Answer 1

Hint: You must have seen red lights are always used in places where caution is needed such as construction sites, traffic lights, etc. Have you wondered what makes it the most suitable color for this?

Complete answer:
Energy can also be used to measure visible light. Frequency is an important property of all waves and the amount of energy contained in each wave is related in proportion to its frequency. The higher the frequency of the wave, the more energy a wave has and vice versa. In our case of visible light, the highest frequency color, which is violet, which means it will have the highest energy. Similarly, red has the lowest frequency, so it will have the least energy.
Mathematically,
\[c=\nu \lambda \]
where, c = speed of light in a vacuum.
\[\nu \] = frequency
\[\lambda \] = wavelength
Now on rearranging,
\[\nu =\dfrac{c}{\lambda }\]
We can see that wavelength is indirectly proportional frequency i.e. as wavelength decreases, frequency increases. Energy (E) can be written as,
\[E=\hbar \nu \]
Where,\[\hbar \] = Planck's constant.
We can conclude that as the wavelength decreases, frequency increases which leads to increase in energy.
Looking at our option, wavelength of each spectrum is:
Violet = 380-450 nm
Green = 495-570 nm
Yellow = 570-590 nm
Orange = 590-620 nm
Red = 620-750 nm

Therefore, the correct option is (a).

Note:
As we can see red light has the highest wavelength, it scatters the least, which is why it can travel longer distances through rain, fog or dust and reach our eyes effectively.