The laser in an audio compact disk player uses light with a wavelength of 7.80x10^2 nm.

(i)What is the frequency, in s^-1 of the light?

(ii)What is the wavenumber, in cm^-1, of the light?

(iii)What is the energy, in J, of a single photon of this light ?

(iv)If an object absorbs a total of 8.85 x 10^3 J of this light, how many photons of this light were absorbed?

so you have 7.80x10^2 nm. = (7.80x10^2) x 10^-9 metres

(i)v = f*lamda

f = v/lamda

f = 3.00 x 10^8 x (7.80x10^2) x 10^-9

f =0.0234 s^-1 = .0243Hz

(ii)Wavenumber is 1/wavelength..

wavenumber is 1.28*10^8 cm^-1

(iii)The Energy in J for a photon of light

(iiii)Is E= hf where h is Planck’s constant (6.626 *10^-34)Js and f is .0234 s^-1

= 1.75*10^-38

Their answer very clear thank you!!

your welcome

But what is (iii)?

E = hv

(6.626 x 10¯^{34} J s) (.0243Hz^{} )

E= .........J

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