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Unformatted text preview: Physics 132
Examples weeks 1 — 4 Example: Determine the frequency heard by the observer. The frequency of a car horn is 400 H z. (a) What frequency is observed if the car is moving toward a stationary observer with a speed of
34 m / 5? The velocity of sound in air is 340 m / s. (b) Same question as in part (a) but the observer is moving away from the source with a velocity
50 m / s at the same time the source is moving toward the observer with a speed of 34 m/s. Example:
A boat is moving with velocity moat toward a cliff. The boat's whistle produces a frequency fboat.
Determine the frequency heard on the boat when the boat's whistle echoes off the cliff. Example String of mass m and length L is tied to a wall at one end. The other end passes over a pulley and
is connected to an oscillator which vibrates with an amplitude A. Essentially both ends of the
string are fixed. The tension in the string is T. Determine the following: (1) The distance between the ﬁrst node of the oscillation away from the wall and the wall when the
string is oscillating in its n = 3 mode. (2) The linear frequency of the source when the string is oscillating in its n = 3 mode. (3) The amplitude of the standing wave. (4) The maximum value of Y where an 2 (5) The maximum transverse speed that any point on the string experiences. (6) The maximum transverse acceleration that any point on the string experiences, Example: A vertical pipe open at both ends is partially submerged in a beaker of water. A tuning fork of
unknown frequency is struck and held above the open end. The pipe is moved relative to the water
and the smallest L which produces a peak in the sound intensity is found. The velocity of sound in
air is 7.). Determine the frequency of the tuning fork and the value of y for the next two resonances. When the pipe is placed in the water, it is essentially a pipe open at one end and closed at the other. Newton‘s rings: A piano—convex lens has an index of refraction n. The curved side of the lens has a radius of
curvature R and rests on a ﬂat glass surface of the same index. Air is between the two surfaces.
The lens is illuminated from above by light of wavelength A. Determine the radii of the dark interference rings formed. Example Two glass plates of length [are supported by a wire of diameter h. _ Determine the spacing of the dark fringes seen when light of wavelength /\ is reﬂected from the
plates. Nonreﬂective coatings We want the minimum thickness which will produce a non—reﬂective coating for a monochromatic
light source of wavelength A. Example A double slit system is illuminated by a light source of a single wavelength A. The separation of
the slits is d. The distance between the screen and the slits is L. Determine the distance on the
screen between the seventh bright fringe above the perpendicular bisector of the slits from the
second bright fringe below that line. Example See Figure 22.20 A Michelson Interferometer has an evacuable cell in one arm of the device. The cell has a length, d, and the light has a wavelength A in a vacuum. When the cell is evacuated,
m fringes are observed to pass the eyepiece Determine the index of refraction of air. Example When interference effects of a double slit are combined with diffraction effects for a slit of finite
width, very often expected interference maxima are found to be missing. If the separation of the
two slits, d, is three times‘the width of a slit, 0., what will be the lowest missing order? Example A grating with slit spacing d is illuminated by light with two separate, identiﬁable wavelengths, A1
and A2. The distance between the viewing screen and the grating is L. Determine the distance
between the two wavelengths in third order on the screen. Example
Two polarizing sheets have their polarizing directions parallel so that the transmitted light intensity is at a maximum. Through what angle must either sheet be turned if the intensity is to drop by one
half. Example
An object is located at the bottom of a swimming pool of depth d. When an individual is looking
almost directly down at the object from the air above, the object appears to be at a different distance below the surface of the water. What is the apparent distance (d’) the object is below the
water's surface? Example A ray of light is incident on a slab of material of thickness t. The index of refraction of the slab is
n. The slab is located in air. Show that the ray of light incident at angle 91 will emerge parallel to
the incident beam. Also determine the displacement, d, of the ray. Example
The distance between a fixed object and its image is l. There are two separate lens locations for a converging lens of focal length f where a sharp image is formed. Calculate the location of these
lens positions. Example Two lenses of focal length f1 and f2 are in contact. Determine the effective focal length of the
combination. Example Two lenses are separated by 10 cm. The focal length of the ﬁrst lens is + 40 cm. The focal length
of the second is + 60 cm. An object of height 3 cm is placed 80 cm in front of the ﬁrst lens.
Determine the location, character (real or virtual), and size of the ﬁnal image formed by the two
lens system. Example
A nearsighted person cannot see objects clearly beyond 4.0 m. Determine the focal length and
power of the appropriate corrective lens. ...
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 Spring '08
 Pompi
 Light, Wavelength

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