Question

a sodium vapour street lamp emits radiation of wavelength 589nm.the frequency of this radiation would be ????

Answer 1

As we know frequency=speed of light/wavelenght

Given wavelenght=589 nm=589*10^-9 m (as 1nm=10^-9m)

speed of light is 3*10^8 m/s

Therefore, frequency=3*10^8/589*10^-9

=5.1*10^14 hz

Answer 2

Concept

The wavelength of a wave is the distance between two consecutive crest (peaks) or a vessel in the waves.

Given

Wavelength given is 589nm

Find

We need to find the frequency

Solution

We know that

Frequency = speed of light / wavelength

Where the speed of light is 3*10^8

Wavelength is 589 x 10^-9

So The frequency will be

3*10^8 /589*10^9

= 0.00509337861*10^17

=509.3378 terahertz

[10^12= tera]

[s^-1] = hertz

Hence the frequency is 509.3378 terahertz

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