Essential University Physics, 3e (Wolfson) 3e (Wolfson) Chapter 30 Reflection and Refraction
3 0. 1 Co nc e pt ua lQue s t i o ns 1) A ray of light goes goe s from one transparent material into another, as shown in the figure. What can you conclude about the indices of refraction of these two materials?
A) n1 ≥ n2 B) n1 n2 !) n1 " n2 #) n2 ≥ n1 $) n2 n1 Answer% B &ar% 1
2) When light goes from one material into another material ha'ing a (*($+ inde of refraction A) its speed, wa'elength, and fre-uency fre-uenc y all decrease. B) its speed and wa'elength decrease, but its fre-uency stays the same. !) its speed decreases but its wa'elength and fre-uency both increase. #) its speed decreases but its fre-uency and wa'elength stay the same. $) its speed increases, its wa'elength decreases, and its fre-uency stays the same. Answer% B &ar% 1
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) A ray of light stri3es a boundary between two transparent materials, and there is no transmitted ray, as shown in the figure. What can you conclude about the indices of refraction of these two materials?
A) n1 ≥ n2 B) n1 n2 !) n1 " n2 #) n2 ≥ n1 $) n2 n1 Answer% B &ar% 1
4) Which one of the following is an accurate statement about light? A) When light stri3es a surface at Brewster5s angle, the reflected and transmitted light are both 1//6 polari7ed. B) When light stri3es a surface at Brewster5s angle, it is completely reflected at the surface. !) When light stri3es a surface at Brewster5s angle, only the reflected light is 1//6 polari7ed. #) When light stri3es a surface at the critical angle, only the reflected light is 1//6 polari7ed. $) When light stri3es a surface at the critical angle, all the light passes through the surface. Answer% ! &ar% 1
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3 0 . 2 Pr o bl e ms 1) A ray of light passes from glass into a li-uid, as shown in the figure. What is the speed of the light in the li-uid? 8c " .// 9 1/: m;s)
Answer% 2.:1 9 1/: m;s &ar% 1
2) cm thic3 sheet of glass at a n angle of incidence in air of =/. @he sheet has parallel faces and the glass has an inde of refraction 1.=/. 8a) What is the angle of refraction in the glass? 8b) After tra'eling through the glass the light re>emerges into the air. What is the final angle of refraction in air? 8c) As it lea'es the glass, by what distance is the path of the ray is displaced from what it was before entering the glass? Answer% 8a) 1 8b) =/ 8c) 1. cm &ar% 1
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A) : B) 1 !) = #) 2 $) == Answer% A &ar% 1
4) An oil layer that is =./ cm thic3 is spread smoothly and e'enly o'er the surface of water on a windless day. What is the angle of refraction in the water for a ray of light that has an angle of incidence of 4= as it enters the oil from the air abo'e? 8@he inde of refraction for the oil is 1.1=, and for water it is 1..) A) 2 B) 2 !) 0 #) $) =2 Answer% B &ar% 1
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=) n the figure, a laser positioned on a ship is used to communicate with a small two>man research submarine resting on the bottom of a la3e. @he laser is positioned 12 m abo'e the surface of the water, and it stri3es the water 2/ m from the side of the ship. @he water is 0 m deep and has an inde of refraction of 1.. (ow far hori7ontally is the submarine from the side of the ship?
A) :4.1 m B) 04.1 m !) 1/4 m #) 4.1 m $) 4.1 m Answer% A &ar% 1
0) A tan3 holds a 1.44>m thic3 layer of oil that floats on a /.0>m thic3 layer of brine. Both li-uids are clear and do not intermi. oint O is at the bottom of the tan3, on a 'ertical ais. @he indices of refraction of the oil and the brine are 1.4/ and 1.=2, respecti'ely. A ray originating at O crosses the brine>oil interface at a point /.0/ m from the ais. @he ray continues and emerges into the air abo'e the oil. What is the angle that the ray in the air ma3es with the 'ertical? A) 4: B) =1 !) =4 #) = $) 0/ Answer% ! &ar% 1
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) @he speed of light in a material is between the material and a 'acuum? A) / B) 21 !) 24 #) 2 Answer% A
What is the critical angle of a light ray at the interface
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:) @he critical angle in air for a particular type o f glass is ./. What is the speed of light in this class glass? 8c " .// 9 1/: m;s) A) 1. 9 1/: m;s B) 1.4 9 1/: m;s !) 1.1 9 1/: m;s #) 1.: 9 1/: m;s $) 2.// 9 1/: m;s Answer% # &ar% 1
) What is the critical angle for light tra'eling from crown glass 8n " 1.=2) into water 8n " 1.)? A) 42 B) 4: !) = #) = $) 01 Answer% $ &ar% 1
1/) An optic fiber is made of clear plastic with inde of refraction of 1.=/, surrounded by air. Cor what angles of incidence θ will light remain within the plastic fiber? A) θ ≥ 21.1 B) θ D :. !) θ :. #) θ D 41.: $) θ 41.: Answer% $ &ar% 1
11) An optical fiber made of glass with an inde of refraction 1.=/ is coated with a plastic with inde of refraction 1./. What is the critical angle of this fiber at the glass>plastic interface? A) /./ B) 41.: !) 0/.1 #) =/.2 $) 01.1 Answer% ! &ar% 1 0 !opyright 2/10 earson $ducation, nc.
12) A glass plate whose inde of refraction is 1.=0 is immersed in a li-uid. @he surface of the glass is inclined at an angle of 42./ with the 'ertical. A hori7ontal ray in the glass is incident on the interface. When the li-uid is a certain alcohol, the incident ray arri'es at the interface at the critical angle. What is the inde of refraction of the alcohol? A) 1./4 B) 1./2 !) 1.// #) /.:4 $) 1./0 Answer% A &ar% =/E
1) A tan3 holds a 1.44>m thic3 layer of oil that floats on a /.0>m thic3 layer of brine. Both li-uids are clear and do not intermi. oint O is at the bottom of the tan3, on a 'ertical ais. @he indices of refraction of the oil and the brine are 1.4/ and 1.=2, respecti'ely. A ray originating at O reaches the brine>oil interface at the critical angle. What is the distance of this point from the ais? A) 1.= m B) 1. m !) 1. m #) 2.1 m $) 2. m Answer% $ &ar% 1
14) A ray of light tra'eling in air stri3es the surface of a certain plastic slab at 0./ with respect to the normal in air. t tra'els in the plastic slab at a /.0 angle with respect to the normal. Cind the critical angle for the plastic in air. Answer% 4.: &ar% =/E
1=) A ray of light consisting of blue light 8wa'elength 4:/ nm) and red light 8wa'elength 0/ nm) is incident on a thic3 piece of glass at :/. What is the angular separation between the refracted red and refracted blue beams while they are in the glass? 8@he respecti'e indices of refraction for the blue light and the red light are 1.400 and 1.4=01.) A) /.2 B) /. !) /.0 #) /.40 $) /.=4 Answer% A &ar% 1
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10) A beam of light of two different wa'elengths enters a pane of glass .// mm thic3 at an angle of incidence of =0. @he indices of refraction for the two different colors are 1.=14 and 1.=2:. Because of dispersion, the colored beams, although parallel, are separated by a small distance. (ow far apart are they? A) /./= mm B) /.//: mm !) /./2= mm #) /./14 mm $) /.//02 mm Answer% # &ar% 1
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1:) @he critical angle for an air>glass interface is 2.0. When a light ray in air is incident on the interface, the reflected ray is 1//6 polari7ed. What is the an gle of refraction of that ray? A) 20. B) 2=. !) 2=.1 #) 24.= $) 2. Answer% A &ar% =/E
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