Bukhovtsev-et-al-Problems-in-Elementary-Physics

PHYSICAL OPTICS
425
~---b---~
Fig. 555
773. The path of the rays in the system is illustrated in Fig. 554. Here
8 1 and 52 are the images of source S in 'the halves of the lens. Obviously,
b=~ a-I
The distance I between 8 1 and 8 2 can be found from the similarity of
triangles SAB and 88 18,:
l=~ a-I
The distance between adjacent interference bands on the screen is
~h= A(D-b)=~(Da_DI_af)=lO-2 cm
I ad
(see Problem 764).
The sought number of interference bands is
d(D+a)=25
a~h
174. The distance between the virtual sources 8. and S2 can be found by
the method described in the solut ion of Problem 773 (Fig. 555).
The distance between interference bands is
6h
A(0/ - [)a +af)
da
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