PHY2054 Summer 2017 Final ExamVersion 2 MULTIPLE CHOICE. Please answer all questions by choosing the one alternative that best completes the statement or answers the question. 1) When two or more capacitors are connected in series across a potential difference, A) the equivalent capacitance of the combination is less than the capacitance of any of the capacitors. B) the potential difference across the combination is the algebraic sum of the potential differences across the individual capacitors. C) each capacitor carries the same amount of charge. D) All of the above choices are correct. E) None of the above choices are correct. 2) A potential difference of 100.0 V is applied across two capacitors in series, as shown in the figure below. If C1 is a 3.0 μf capacitor and has a voltage drop of 75 V across it, what is the capacitance of C2? C1 C2 100 V A) 0.75 μf B) 9.0 μf C) 1.0 μf D) 2.3 μf 3) The energy flow per unit time per unit area (S) of an electromagnetic wave has an average value of 680 mw/m 2. The wave is incident upon a rectangular area, 1.5 m by 2.0 m, at right angles. The total energy that traverses the area in a time interval of one minute is closest to: A) 240 J B) 120 J C) 210 J D) 150 J E) 180 J 1
4) The figure below shows three identical lightbulbs connected to a battery having a constant voltage across its terminals. What happens to the brightness of lightbulb 1 when the switch S is closed? (Hint: the brightness of the bulb is proportional to the current flowing through the bulb) A) The brightness increases permanently. B) The brightness will decrease momentarily then return to its previous level. C) The brightness decreases permanently. D) The brightness will increase momentarily then return to its previous level. E) The brightness remains the same as before the switch is closed. 5) One very small uniformly charged plastic ball is located directly above another such charge in a test tube as shown in the figure. The balls are in equilibrium a distance d apart. If the charge on each ball is doubled, the distance between the balls in the test tube would become (Recall: F = ma) A) 4d. B) 8d. C) 2d. D) 2d. 2
6) A conductor is formed into a loop that encloses an area of 2.0 m2. The normal direction of the loop is oriented at a 30.0 angle with the xy-plane. A varying magnetic field is oriented parallel to the z-axis. If the maximum emf induced in the loop is 39.0 V, what is the maximum rate at which the magnetic field strength is changing? A) 39 T/s B) 23 T/s C) 17 T/s D) 10 T/s 7) In the figure below, a battery supplies a steady current to the solenoid on the left. The two solenoids are moving toward each other. The induced current through the resistor R is: A) from b to a B) zero C) from a to b 8) A circular coil of wire of 200 turns and diameter 9 cm carries a current of 3 A. It is placed in a magnetic field of 0.60 T with the normal to the coil making an angle of 60 with the magnetic field. What is the torque on the coil? A) 0.99 N m B) 1.1 N m C) 5.2 N m D) 2.0 N m E) 3.8 N m 9) A myopic (nearsighted) girl wears eyeglasses that allow her to have clear distant vision. The power of the lenses of her eyeglasses is -0.50 diopters. Without eyeglasses, the far point of the girl is closest to: A) 1.0 m B) 1.5 m C) 2.0 m D) 3.0 m E) 2.5 m 3
10) Consider the group of charges in the figure below. All three charges have Q = 8.8 nc. What is their electric potential energy? A) 5.5 10-5 J B) 5.9 10-5 J C) 6.2 10-5 J D) 5.7 10-5 J 11) 55 In the figure above, a ray in glass arrives at the glass-water interface at an angle of 48 with the normal. The refracted ray, in water, makes a 55 angle with the normal. The index of refraction of water is 1.33. If the angle of incidence of a different ray in the glass is now 37. The angle of refraction in the water is closest to: A) 65 B) 67 C) 42 D) 61 E) 69 12) How much current will be flowing through a 70.0 m length of copper wire with radius 7.0 mm if it is connected to a source supplying 18.0 V? (The resistivity of copper is 1.68 10-8 Ω m.) A) 11 108 A B) 1400 A C) 44nA D) 2400 A 4
13) The radius of curvature of the curved side of a plano-convex lens made of glass (n = 1.64) is 46 cm. What is the focal length of the lens? A) -29 cm B) 29 cm C) 72 cm D) -72 cm 14) The electric field at point P due to a point charge Q a distance R away has magnitude E. In order to double the magnitude of the field at P, you could A) reduce the distance to R/2. B) reduce the distance to R/4. C) double the charge to 2Q. D) double the charge to 2Q and at the same time reduce the distance to R/2. E) double the distance to 2R. 15) An oject 3.4 mm tall is placed 25 cm from the vertex of a convex spherical mirror. The radius of curvature of the mirror has a magnitude of 52 cm. How far is the image from the vertex of the mirror? A) 13 cm B) 130 cm C) 1.7 mm D) 17 mm 16) In a compound microscope A) both the objective and the eyepiece form real images. B) the image of the objective serves as the object for the eyepiece. C) The magnification is m1 + M2, where m1 is the lateral magnification of the objective and M2 is the angular magnification of the eyepiece. D) magnification is provided by the objective lens and not by the eyepiece. The eyepiece merely increases the resolution of the image viewed. E) magnification is provided by the objective and not by the eyepiece. The eyepiece merely increases the brightness of the image viewed. 5
17) A single slit forms a diffraction pattern, with the first minimum at an angle of 40 from central maximum. Monochromatic light of 550 nm wavelength is used. The width of the slit, in nm, is closest to: A) 856 B) 750 C) 785 D) 821 E) 715 18) The three loops of wire shown in the figure are all subject to the same uniform magnetic field B that does not vary with time. Loop 1 oscillates back and forth as the bob in a pendulum, loop 2 rotates about a vertical axis, and loop 3 oscillates up and down at the end of a spring. Which loop, or loops, will have an emf induced in them? A) loops 1 and 2 B) loop 3 only C) loop 2 only D) loop 1 only E) loops 2 and 3 19) Which one of the following lists is a correct representation of electromagnetic waves from longer wavelength to shorter wavelength? A) radio waves, UV, X-rays, microwaves, infrared, visible, gamma rays B) radio waves, microwaves, infrared, visible, UV, X-rays, gamma rays C) radio waves, microwaves, visible, X-rays, infrared, UV, gamma rays D) radio waves, infrared, microwaves, UV, visible, X-rays, gamma rays E) radio waves, infrared, X-rays, microwaves, UV, visible, gamma rays 6
20) In the two-slit experiment, monochromatic light of frequency 5.00 x 10 14 Hz passes through a pair of slits separated by 2.20 x 10-5 m ( c = 3.00 x 10 8 m/s). At what angle away from the central bright spot does the third bright fringe past the centre spot occur? A) 2.30 0 B) 4.69 0 C) 1.40 0 D) 8.42 0 21) In the circuit shown below, what current does the ammeter read? 30.0 Ω 80.0 Ω 30.0 Ω 6.0 V 10.0 V 80.0 Ω A) 0.16 A B) 0.13 A C) 0.33 A D) 0.63 A 22) A 360 nm thick oil film floats on the surface of the water. The indices of refraction of the oil and the water are 1.50 and 1.33, respectively. The surface of the oil is illuminated from above at normal incidence with white light. The two wavelengths of light in the 400 nm to 800 nm wavelength band that are most strongly reflected, in nm, are closest to: A) 430 and 720 B) 410 and 700 C) 470 and 760 D) 450 and 740 E) 490 and 780 7
23) Four charged particles (two having a charge +Q and two having a charge -Q) are distributed as shown in the figure below. Each charge is equidistant from the origin. In which direction is the net electric field at the point P, which is on the y axis? A) the net field is zero, so there is no direction B) upwards, towards the left C) directly up (in the positive y direction) D) upwards, towards the right E) directly left (negative x direction) 24) A uniform magnetic field of magnitude 0.80 T in the negative z-direction is present in a region of space. A uniform electric field is also present. In the figure above, the electric field is set at 52,800 V/m in the positive y-direction. An electron is projected with an initial velocity vo = 6.6 10 4 m/s in the positive x-direction. The y-component of the initial force on the electron is closest to: A) zero B) -8 10-15 N C) -2 10-14 N D) +2 10-14 N E) +8 10-15 N 8
Answer Key Testname: PHY2054 FINAL B 1) D 2) B 3) B 4) A 5) D 6) A 7) C 8) D 9) C 10) A 11) C 12) D 13) C 14) C 15) A 16) B 17) A 18) C 19) B 20) B 21) C 22) A 23) B 24) C 9