PHY2061
R. D. Field
Solutions
Chapter 42
Page 1 of 2
Chapter 42 Solutions
Problem 1:
If monochromatic light of wavelength
500 nm
is incident on a single narrow
slit
0.02 mm
wide, what is the width of the central bright spot (
in cm
) on a
screen that is
3 meters
from the slit? (Hint:
the width of the central bright
spot is equal to the distance between the two first order minima.)
Answer:
15
Solution:
The angular position of the first dark fringe is given by
W
λ
θ
θ
=
≈
sin
,
and
L
y
=
≈
θ
θ
tan
.
Thus, the width of the central bright spot,
D = 2y
, is given by
cm
m
m
m
L
W
y
D
15
)
3
(
10
02
.
0
)
10
500
(
2
2
2
3
9
=
×
×
=
=
=
−
−
λ
.
Problem 2:
Monochromatic light of wavelength
600 nm
is incident on a single narrow
slit and produces a diffraction pattern on a screen
2 meters
away?
If the
screen is moved
1 meter
further away from the slit, what wavelength of
monochromatic light (
in nm
) will produce a diffraction pattern with all the
diffraction minima at the same points on the screen?
Answer:
400
Solution:
The angular position of the dark fringes is given by
W
m
λ
θ
θ
=
≈
sin
,
and
L
y
=
≈
θ
θ
tan
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '08
 FRY
 Physics, Light, Wavelength, Orders of magnitude, Metre, 1m, central bright spot

Click to edit the document details