Exam Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A fish appears to be 7.00 m below the surface of a pond when viewed almost directly above by 1) a fisherman. What is the actual depth of the fish? ( n water � 1.33) A) 0.19 m B) 5.26 m C) 9.31 m D) 0.11 m 2) A light ray (red) enters a concentrically cladded optical fiber at its center and an angle of 26.0° 2) to the axis of the fiber. The diameter of the fiber is 1.0 mm and its refractive index is n f � 1.46. What must be the value of n cladding to guarantee total internal reflection? ( n air � 1.00) A) 1.39 B) 2.03 C) 1.31 D) 1.22 3) A double � concave lens has equal radii of curvature of 15.1 cm. An object placed 14.2 cm from 3) the lens forms a virtual image 4.60 cm from the lens. What is the index of refraction of the lens material? A) 2.11 B) 1.96 C) 2.03 D) 2.19 4) An astronomical telescope is made from two lenses: the objective lens has a focal length of 4) f � 343 cm, and the eyepiece lens has a focal length of f � 9.0 cm. (a) What is the total length of the telescope? (b) What is the angular magnification of the telescope? (c) What is the magnification if the telescope is viewed by looking through the objective lens first? A) (a) 352 cm B) (a) 668 cm C) (a) 704 cm D) (a) 334 cm (b) 38.11 (b) 1.03 (b) 0.97 (b) 0.03 (c) 0.03 (c) 0.97 (c) 1.03 (c) 38.11 5) Astronomers are proud of their telescopes, and often say they can "resolve a dime at so many 5) miles." How many miles can you move a disk ( D � 6.0 cm) from a 325 � cm � diameter telescope mirror and just resolve it using light of wavelength 785 nm? A) 31 mi B) 610,000,000 mi C) 61 mi D) 130 mi 6) Three charges of magnitude 9.0 x 10 � 4 C each are located at x � 1.0 m, y � 0.0 m, at x � 0.0 m, 6) y � 0.0 m, and at x � � 1.0 m, y � 0.0 m. The one in the middle is negative, while the other two are positive. What is the net Coulombic force exerted by them on a negative 9.0 x 10 � 5 C charge located at x � 0.0 m, y � 2.0 m? (The value of k is 9.0 x 109 N � m2/C2.) A) 1100 N attractive B) 790 N repulsive C) 1100 N repulsive D) 790 N attractive ^ N force. What is the electric field at the location of the 4.0 C 7) A 4.0 C charge experiences a 45.0 i 7) charge? ^ N/C ^ N/C ^ N/C ^ N/C B) � 14 i D) � 3.6 i A) 3.6 i C) 14 i 8) A thin wire 1.0 m long has a charge of 1.0 nC. Find the electric field strength 2.0 mm from the 8) end of the wire along the axis of the wire. (The value of k is 9.0 x 10 9 N � m2/C2.) A) 2.3 x 106 N/C B) 4500 N/C C) 1.1 N/C D) 2.3 N/C 1
9) In the figure below d � 7.2 cm. What is the electric field at the position indicated by the dot in 9) the figure? A) 1.0 x 104 N/C, at 5.2° below the horizontal B) 1.1 x 104 N/C, at 5.2° below the horizontal C) 1.1 x 104 N/C, at 8.5° below the horizontal D) 1.0 x 104 N/C, at 8.5° below the horizontal 10) An equilateral triangle is formed from three rods, each of length 10 cm. Two of the rods carry 10) charge � 63 nC uniformly distributed along the length of each rod, while the third carries charge � 63 nC, also uniformly distributed along the rod. What is the magnitude of the electric field at the center of the triangle? A) 1.0 x 106 N/C B) 2.3 x 105 N/C C) 9.3 x 105 N/C D) 6.8 x 105 N/C 11) The figure shows a thin rod of length L � 5.0 cm with total charge Q � 9.5 nC. What is the 11) magnitude of the electric field E at x � 3.0 cm? A) 9.5 x 104 N/C B) 3.1 x 105 N/C D) 4.2 x 105 N/C C) 2.0 x 105 N/C 12) A thin, flexible rod of length L � 10 cm carries charge Q � 83 nC uniformly along its length. 12) The rod is then bent into a semicircle, as shown in the figure. What is the magnitude of the electric field at the center? A) 4.4 x 105 N/C B) 4.7 x 105 N/C C) 3.9 x 105 N/C D) 4.2 x 105 N/C 2
13) What is the electric field strength if the flux through a 2.0 m by 1.0 m rectangular surface is 13) 800.0 N � m2/C, if the electric field is uniform, and if the plane of the surface is at an angle of π/3 radians with respect to the direction of the field? A) 800 N/C B) 400 N/C C) 460 N/C D) 200 N/C 14) A flat 1.0 m2 surface is vertical at x � 2.0 m and parallel to the yz � plane. What is the flux 14) through the surface if it is located in a uniform electric field given by ^ � 42.0 j ^ � 62.0 k ^ N/C? E � 29.0 i A) 42 N � m2/C B) 100 N � m2/C C) 29 N � m2/C D) 62 N � m2/C 15) Four dipoles, each consisting of two charges ±5.0 μC, are located in the xy � plane 3.0 mm from 15) the origin, as shown. What is the flux through the sphere? 3.0 � 3.0 3.0 � 3.0 A) 2.3 x 106 N � m2/C B) 4.5 x 106 N � m2/C C) 0 N � m2/C D) 5.6 x 105 N � m2/C 3
Answer Key Testname: UNTITLED1 1) C 2) C 3) A 4) A 5) C 6) D 7) C 8) B 9) A 10) D 11) B 12) B 13) C 14) C 15) A 4
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