Question

The wavelength of some orange light is $620.0nm$. What is the frequency of this orange light?

Answer 1

Hint: To solve this question, we need to understand the relationship between the frequency of light and its wavelength. So, the relationship between the frequency of light and the wavelength of light is,
$f = \dfrac{v}{\lambda }$
Where,
$f$ is the frequency of light
$v$ is the speed of light
$\lambda $ is the wavelength of light


Complete step by step answer:
Frequency describes the number of waves that pass a fixed place in a given amount of time. The SI unit of frequency is Hertz which is named after the German physicist Heinrich Hertz. It is represented as Hz. Wavelength is defined as the distance travelled by a wave during the time a particle of the medium completes one vibration. The SI unit of wavelength is metre.
We know that $f = \dfrac{v}{\lambda }........(1)$
In this question, it is given $\lambda = 620nm$
On converting it into metre, we get,
$\lambda = 620 \times {10^{ - 9}}m$
$\lambda = 6.2 \times {10^{ - 7}}m$
Also, we know that $v = 3 \times {10^8}\dfrac{m}{s}$
On putting the value of $\lambda $ and $v$ in equation (1), we get,
$f = \dfrac{{3 \times {{10}^8}}}{{6.2 \times {{10}^{ - 7}}}}$
On solving this,
$f = 4.839 \times {10^{14}}hz$
So, the frequency of this orange light is $f = 4.839 \times {10^{14}}hz$.

Additional information: When we talk about visible light, then, violet colour has the highest frequency and the shortest wavelength. This also means that the violet colour has the highest energy also. Similarly, the red colour has the lowest frequency and the longest wavelength. This also means that violet colour has the least energy.

Note: There is an inverse relationship between wavelength and frequency of a light. This means that if a light has longer wavelength, then it will have lower frequency. Similarly, if a light has a shorter wavelength, then it will have a higher frequency.