A student tests the emission spectra of various known substances and an unknown substance. Which statement is a qualitative observation of the tests? A. Two emission lines were seen in the spectra between 400 and 500 nm.

B. The unknown substance contains barium ions.

C. Sodium produces a yellow flame when heated.

D. Nitrate ions have no effect on the color emission.

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Aspecified volume of space contains an electric field for which the magnitude is given by e=e0cos(ωt). suppose that e0 = 20 v/m and ω = 1.0 × 107 s−1. part a what is the maximum displacement current through a 0.80 m2 cross-sectional area of this volume? express your answer with the appropriate units. idisp,max i d i s p , m a x = nothing nothing request answer part b how would this area have to be oriented relative to the electric field to get this maximum displacement current?