[填空题]
If a soap bubble is 120a; y avui8wh,h4.-p /rp ywnz+ nm ,r darmp )-tnq0a+gd+.pbj 2a thick, what wavelength is most strongly reflected at the center of the outer surface when illuma-d.p+ dja), 2 nbq0p+tarmr ginated normally by white light? Assume that $n\;=\;1.34$. $\lambda$ = nm ,which is an -