Peoples Physics Book Version-3

17.1. The Big Idea http://www.ck12.org

nisinθi=nfsinθf

MEDIA

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mλ=dsinθ

Double slit interference maxima.mis the order of the interference maximum in question,dis the distance between
slits. andθis the angular position of the maximum.

mλ=dsinθ

Single slit interference maxima.mandθare defined as above anddis the width of the slit.

mλ=dsinθ

Diffraction grating interference maxima.mandθare defined as above anddis the distance between the lines on the
grating.

mλ= 2 nd

Thin film interference:nis the index of refraction of the film,dis the thickness of the film, andmis an integer.
In the film interference, there is aλ/2 delay (phase change) if the light is reflected from an object with an index of
refraction greater than that of the incident material.

1

f

=

1

d 0

+

1

di

For lenses, the distance from the center of the lens to the focus isf. Focal lengths for foci behind the lens are positive
in sign. The distance from the center of the lens to the object in question isd 0 , where distances to the left of the
lens are positive in sign. The distance from the center of the lens to the image isdi. This number is positive for real