Chemistry, 28.01.2020 20:07 quissowavyquis4808

The wavelength of some violet light is 420.0 nm. what is the frequency of this violet light?

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Answer from: gm2

The frequency of violet light with a wavelength of 420 nm is $\boxed{7.14 \times {\text{1}}{{\text{0}}^{16}}{\text{ }}{{\text{s}}^{ - 1}}}$ .

Further explanation:

Wavelength is the characteristic property of a wave. It is defined as the distance between two successive crests or troughs. A crest is that point where there is maximum displacement of the medium whereas trough is a point that has minimum displacement of the medium. It is represented by $\lambda$ and its SI unit is meter (m).

Frequency is defined as the number of times n event occurs in unit time. It is generally applied to waves including light, sound and radio waves. It is denoted by ${\nu }$ and its SI unit is Hertz (Hz).

The formula to calculate the frequency of violet light is as follows:

$\nu = \frac{c}{\lambda }$ ...... (1)

Here,

c is the speed of violet light.

$\nu$ is the frequency of violet light.

$\lambda$ is the wavelength of violet light.

Firstly, the wavelength is to be converted into m. The conversion factor for this is,

${\text{1 nm}} = {10^{ - 9}}\;{\text{m}}$

So the wavelength of violet light can be calculated as follows:

$\begin{aligned}\lambda&=\left({{\text{420 nm}}}\right)\left({\frac{{{{10}^{-9}}\;{\text{m}}}}{{{\text{1 nm}}}}}\right)\\&=4.2\times {10^{-9}}\;{\text{m}}\\\end{aligned}$

The value of the wavelength of violet light is $4.2 \times {10^{ - 9}}\;{\text{m}}$ .

The value of the speed of violet light is $3 \times {10^8}\;{\text{m/s}}$ .

Substitute these values in equation (1).

$\begin{aligned}\nu&=\left({\frac{{3\times{{10}^8}\;{\text{m}}}}{{{\text{1 s}}}}} \right)\left( {\frac{1}{{4.2 \times {{10}^{-9}}\;{\text{m}}}}}\right)\\&=0.7142{\text{8}} \times {\text{1}}{{\text{0}}^{17}}{\text{ }}{{\text{s}}^{-1}}\\&=7.14\times {\text{1}}{{\text{0}}^{16}}{\text{ }}{{\text{s}}^{ - 1}} \\ \end{aligned}$

Learn more:

1. Statement about subatomic particle: link

2. The energy of a photon in light: link

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Structure of the atom

Keywords: wavelength, frequency, 420 nm, wavelength of violet light, speed of violet light, frequency of violet light, 3*10^8 m/s, 7.14*10^16 s-1, c, distance, crest, trough.

Answer from: Quest

the correct answer is:

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Answer from: Quest

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