Question

If the wavelength of green light is about $5000{A^o}$ , then the frequency of it’s wave is-
A: $16 \times {10^{14}}{\sec ^{ - 1}}$
B: $16 \times {10^{ - 14}}{\sec ^{ - 1}}$
C: $6 \times {10^{14}}{\sec ^{ - 1}}$
D: None

Answer 1

We already know that Green light falls in the visible region of light. The wave velocity of light is constant and the value of that constant speed is $3 \times {10^8}m{\sec ^{ - 1}}$. Light is considered to be the fastest possible thing. The range of visible region light is in between $400nm - 700nm$ .

Complete step by step answer:
We know that light has a constant speed of $3 \times {10^8}m{\sec ^{ - 1}}$ . The wave velocity of a wave can be directly calculated by using the formula $v = \lambda f$ . Here $v =$velocity of the wave,$\lambda =$wavelength of the wave, $f =$frequency of the wave. The value of the wavelength is given in the question and we already know the value of the speed of light . So by directly applying the formula
$f = \dfrac{v}{\lambda } = \dfrac{{3 \times {{10}^{^8}}}}{{5 \times {{10}^{ - 7}}}} = 6 \times {10^{14}}{\sec ^{ - 1}}$.

So, the correct answer is Option C.

Note:
The energy of a wave is directly proportional to the wave’s frequency. Gamma rays have the highest frequency , so it has the highest energy. For this reason gamma rays are harmful for human beings .Gamma rays are used in medical science to spot tumors and to treat cancer. Radio waves have very less frequency and it has the least energy . Among the visible rays , the red coloured waves have the longest wavelength and the violet colour have the least wavelength in the visible region. This is the reason why we can see the sky turning red-orange during sunset and sunrise over the horizon.

Always remember that the speed of light is $v = 3 \times {10^8}$ . And to find the relation between speed, frequency and the wavelength of a given wave use the formula $v = f\lambda$ . Here $v =$velocity of the wave,$\lambda =$wavelength of the wave, $f =$frequency of the wave.