This preview shows page 1. Sign up to view the full content.
39. (a) The angular positions
θ
of the bright interference fringes are given by
d
sin
=
m
λ
,
where
d
is the slit separation,
λ
is the wavelength, and
m
is an integer. The first
diffraction minimum occurs at the angle
1
given by
a
sin
1
=
λ
, where
a
is the slit width.
The diffraction peak extends from –
1
to +
1
, so we should count the number of values of
m
for which –
1
<
< +
1
, or, equivalently, the number of values of
m
for which – sin
1
< sin
< + sin
1
. This means – 1/
a < m
/
d
< 1/
a
or –
d
/
a < m < +d
/
a
. Now
d
/
a
= (0.150
×
10
–3
m)/(30.0
×
10
–6
m) = 5.00,
so the values of
m
are
m
= –4, –3, –2, –1, 0, +1, +2, +3, and +4. There are 9 fringes.
This is the end of the preview. Sign up
to
access the rest of the document.
This note was uploaded on 06/03/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.
 Spring '08
 Any
 Physics, Diffraction

Click to edit the document details