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Physics 208 Review Questions - Final
1. A pane of glass (n = 1.5) is coated with a 80.0 nm thick layer of a special
coating (n = 1.32) in order to prevent reflections in the visible spectrum.
What is the longest wavelength that will be strongly reflected?
2. Mobile phones rely on electromagnetic waves with wavelengths of
approximately 0.300 meters. If you were to stand about 10 meters away from
a wall which was made up of tall, thin metal beams separated by half a meter,
(like an elephant cage or something) would there be any noticeable
intereference effects due to the metal beams? (The metal beams will shield
the em radiation.) Quantitatively describe the intereference produced by such
an arrangement.
3. The normal relaxed length of the spring shown is
7 cm. We hang it from the ceiling with a 5 gram
mass on it. Directly below it is another mass with a
charge of 1 μC. The system comes to equilibrium
as shown in the diagram. If the spring constant is
50 N/m, what is the charge of the 5 gram mass.
30 cm
q1
20 cm
q2
4. A metal loop (width = 40 mm, height = 50 mm) is moving at a speed of
0.03 m/s in the +x direction through a non-uniform magnetic field. The
plane of the loop of perpendicular to the magentic field direction. At x =
0.03 m, the field strength is 10 mT. This value increases lineaerly such that at
x = 0.09 m, the B-field magnitude is now 60 mT. What is the induced emf in
the loop?
Physics 208 Review Questions - Final
1. A pane of glass (n = 1.5) is coated with a 80.0 nm thick layer of a special
coating (n = 1.32) in order to prevent reflections in the visible spectrum.
What is the longest wavelength that will be strongly reflected?
2. Mobile phones rely on electromagnetic waves with wavelengths of
approximately 0.300 meters. If you were to stand about 10 meters away from
a wall which was made up of tall, thin metal beams separated by half a meter,
(like an elephant cage or something) would there be any noticeable
intereference effects due to the metal beams? (The metal beams will shield
the em radiation.) Quantitatively describe the intereference produced by such
an arrangement.
3. The normal relaxed length of the spring shown is
7 cm. We hang it from the ceiling with a 5 gram
mass on it. Directly below it is another mass with a
charge of 1 μC. The system comes to equilibrium
as shown in the diagram. If the spring constant is
50 N/m, what is the charge of the 5 gram mass.
30 cm
q1
20 cm
q2
4. A metal loop (width = 40 mm, height = 50 mm) is moving at a speed of
0.03 m/s in the +x direction through a non-uniform magnetic field. The
plane of the loop of perpendicular to the magentic field direction. At x =
0.03 m, the field strength is 10 mT. This value increases lineaerly such that at
x = 0.09 m, the B-field magnitude is now 60 mT. What is the induced emf in
the loop?
5. A circular region of space has a radius of 0.25 m. In this region there is a
magnetic field directed in the positive z axis that is increasing at a rate of 0.30
T/s. Find the strength of the induced electric field at a) a point 20 cm from
the center, and b) at a point half a meter from the center. Sketch the region
and include your coordinate system and the show the direction of the B and
E fields using vectors.
6. A ring of conducting material is located in a uniform magnetic field. The
field strength is constant in time, but the radius of the ring is increasing at a
rate given by
where is a constant. Find an expression for the
induced emf in the ring as a function of time.
7. What is the critical angle for a fiber optic cable surrounded by air if the
index of refraction of the cable is a) 1.4 and b) 1.8 ? Which could
accomodate a tighter bend and still maintain total internal reflection?
8. Lens 1, which has a focal length of 10 cm is located 15 cm to the left of
lens two, which has a focal length of -8 cm. An object is placed 18 cm to the
left of Lens 1. What is the distance between lens 2 and the image it produces.
What is the total magnification of the object -> final image.
5. A circular region of space has a radius of 0.25 m. In this region there is a
magnetic field directed in the positive z axis that is increasing at a rate of 0.30
T/s. Find the strength of the induced electric field at a) a point 20 cm from
the center, and b) at a point half a meter from the center. Sketch the region
and include your coordinate system and the show the direction of the B and
E fields using vectors.
6. A ring of conducting material is located in a uniform magnetic field. The
field strength is constant in time, but the radius of the ring is increasing at a
rate given by
where is a constant. Find an expression for the
induced emf in the ring as a function of time.
7. What is the critical angle for a fiber optic cable surrounded by air if the
index of refraction of the cable is a) 1.4 and b) 1.8 ? Which could
accomodate a tighter bend and still maintain total internal reflection?
8. Lens 1, which has a focal length of 10 cm is located 15 cm to the left of
lens two, which has a focal length of -8 cm. An object is placed 18 cm to the
left of Lens 1. What is the distance between lens 2 and the image it produces.
What is the total magnification of the object -> final image.