Question

The wavelength of a beam of light is 25.0 um. Its wavenumber is :​

Answer 1

Answer:

Wavelength of a light beam is 25 micrometre , it`s wave number is-(1)4.0×10^2 cm^-1 (2)4.0×10^6 cm^-1 (3)4.0×10^6 m^-1 (4)25.0×10^4 cm^-

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Answer 2

Answer:  wave no. = 1/wavelength

wave no. =  

1

2.5 ×

10

−9  

= 4 ×

10

8

 

m

−1

Energy = no. of photon × planck's constant ×frequency

E = 1 ×6.626 ×

10

−34  

Js×1.2 ×

10

17

 

s

−1

E = 7.95 ×

10

−17

J

(a) 1 nm = 10-7 cmso 2.5 nm = 2.5 ×10-7 cm(b) frequency = speed of light in vaccumwavelength of lightfre. = 3×1082.5 ×10-9 s-1fre. = 1.2 ×1017 s-1(c) wave no. = 1/wavelength wave no. = 12.5 ×10-9 = 4 ×108 m-1Energy = no. of photon × planck's constant ×frequencyE = 1 ×6.626 ×10-34 Js×1.2 ×1017 s-1E = 7.95 ×10-17 J