Calculate the dot product of D and E, where D=7i - 3j + 2k and E=4i + 5j - 3k. please show working

Since i dot i = 1  and  j dot j = 1 and k dot k = 1 and the other terms are zero

(7 i - 3 j + 2 k) dot (4 i  + 5 j - 3 k) = 28 - 15 -6  = 7

absorption lines are where light has been absorbed by the atom thus you see a dip in the spectrum whereas.

emission spectra have spikes in the spectra due to atoms releasing photons at those wavelengths.

explanation:

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