Calculate the frequency of radiation with a wavenumber of [tex]97540 \, \text{cm}^{-1}[/tex].

1. [tex]2.926 \times 10^{10} \, \text{S}^{-1}[/tex]
2. [tex]2.926 \times 10^{15} \, \text{S}^{-1}[/tex]
3. [tex]2.926 \times 10^2 \, \text{S}^{-1}[/tex]
4. [tex]2.926 \times 10^{20} \, \text{S}^{-1}[/tex]



Answer :

To find the frequency of a radiation given its wavenumber, we can use the relationship between wavenumber and frequency. The wavenumber ([tex]\(\bar{\nu}\)[/tex]) is defined as the number of wavelengths per unit distance, and is typically measured in [tex]\( \text{cm}^{-1} \)[/tex]. The formula to convert wavenumber to frequency ([tex]\(\nu\)[/tex]) is given by:

[tex]\[ \nu = \bar{\nu} \cdot c \][/tex]

where:
- [tex]\(\nu\)[/tex] is the frequency.
- [tex]\(\bar{\nu}\)[/tex] is the wavenumber.
- [tex]\(c\)[/tex] is the speed of light.

The speed of light, [tex]\(c\)[/tex], is [tex]\(2.998 \times 10^{10} \, \text{cm/s}\)[/tex].

Given:
[tex]\[ \bar{\nu} = 97540 \, \text{cm}^{-1} \][/tex]

Now, substituting the given values into the formula:

[tex]\[ \nu = 97540 \, \text{cm}^{-1} \times 2.998 \times 10^{10} \, \text{cm/s} \][/tex]

When this calculation is performed (multiplying 97540 by 2.998 and the power of 10 terms), the result is:

[tex]\[ \nu \approx 2.9242492 \times 10^{15} \, \text{s}^{-1} \][/tex]

Therefore, the correct answer is:

2) [tex]\(2.926 \times 10^{15} \, \text{s}^{-1} \)[/tex]

This matches the calculated frequency closely because the given answer choice is closest to the exact frequency calculated above.