The color of light can be expressed in terms of either frequency [tex]\((v)\)[/tex] or wavelength [tex]\((\lambda)\)[/tex], which has units of nanometers (nm). The equation that relates the frequency and wavelength of light with the speed of light (c) is:

[tex]\[ v = \frac{c}{\lambda} \][/tex]

The speed of light is a constant and approximately equal to [tex]\(300,000,000\)[/tex] meters per second. Green lasers emit light at a wavelength of [tex]\(532 \, \text{nm}\)[/tex]. However, the material that is used to make most green lasers does not emit light at [tex]\(532 \, \text{nm}\)[/tex]. Instead, it emits light at a different wavelength, and the laser then uses a "frequency doubler." This doubles the frequency of the emitted light, and the resultant light is the green [tex]\(532 \, \text{nm}\)[/tex] that we observe.

1 meter is equal to [tex]\(1,000,000,000\)[/tex] nanometers.

What is the output light frequency of the material used before doubling?

You may use a calculator.

A. [tex]\(1.8 \times 10^{14} \, \text{Hz}\)[/tex]
B. [tex]\(2.8 \times 10^{14} \, \text{Hz}\)[/tex]
C. [tex]\(5.6 \times 10^{14} \, \text{Hz}\)[/tex]
D. [tex]\(1.1 \times 10^{15} \, \text{Hz}\)[/tex]



Answer :

To solve the problem, let's break it down step by step.

1. Understand the given data and constants:
- Speed of light, [tex]\( c = 300,000,000 \text{ meters per second} \)[/tex]
- Wavelength of green laser light, [tex]\( \lambda = 532 \text{ nanometers} \)[/tex]
- Conversion factor, [tex]\( 1 \text{ meter} = 1,000,000,000 \text{ nanometers} \)[/tex]

2. Convert the wavelength from nanometers to meters:
[tex]\[ \lambda_{\text{green}} = \frac{532 \text{ nm}}{1,000,000,000} = 532 \times 10^{-9} \text{ meters} = 5.32 \times 10^{-7} \text{ meters} \][/tex]

3. Calculate the frequency of the green laser light using the formula:
[tex]\[ v = \frac{c}{\lambda} \][/tex]
Substituting the values,
[tex]\[ v_{\text{green}} = \frac{300,000,000 \text{ m/s}}{5.32 \times 10^{-7} \text{ m}} \approx 563,909,774,436,090.1 \text{ Hz} \][/tex]

4. Determine the frequency of the material before doubling:
Given that the material emits light which is then doubled in frequency,
[tex]\[ v_{\text{before doubling}} = \frac{v_{\text{green}}}{2} = \frac{563,909,774,436,090.1 \text{ Hz}}{2} \approx 281,954,887,218,045.06 \text{ Hz} \][/tex]

5. Compare to the given options:

[tex]\[ \approx 2.8 \times 10^{14} \text{ Hz} \][/tex]

Therefore, the correct answer is:

B. [tex]\(2.8 \times 10^{14} \text{ Hz}\)[/tex]