Physics 112 N Midterm Exam: Magnetic Fields, Lenses, and Optics, Exams of Physics

Download Physics 112 N Midterm Exam: Magnetic Fields, Lenses, and Optics and more Exams Physics in PDF only on Docsity! You may write your answers on this booklet. Please hand in your formula sheet along with your answers It is in your interest to show working when- ever possible. You have 70 minutes to complete as much of the test as you can μ0 = 4π × 10 -7 N/A2 c = 3.00 × 108 m/s sign conventions for mirrors: ‣ the radius of curvature is positive when the center of curvature lies on the side of outgoing rays ‣ the object distance is positive when the object lies on the same side as the incoming rays ‣ the image distance is positive when the image lies on the same side as the outgoing rays sign conventions for lenses: ‣ converging lenses have positive focal length, diverging lenses have negative focal length ‣ the object distance is positive when the object lies on the same side of the lens as the incoming rays ‣ the image distance is positive when the image lies on the same side of the lens as the outgoing rays some unit conversions: T = N / (A m) Wb = T m2 A = C / s T = V s / m2 Physics 112 N Midterm Exam Name: Student ID: 1 A long straight wire carries a current of 0.10 A as shown. What is the direction of the magnetic field at the point A? (a) to the right (b) upward (c) into the page (d) out of the page What is the magnitude of the magnetic field? (a) 1.0 T (b) 1.0 x 10-6 T (c) 2.0x10-6 T (d) 1.0x10-6 Wb (e) 2.0x10-8 Wb 2 Three particles move through a uniform magnetic field following the paths shown. For each particle indicate whether it is positively charged, negatively charged or neutral. 1. positive / negative / neutral 2. positive / negative / neutral 3. positive / negative / neutral The force on particle 3 is measured to be 1.0x10-6 N while it is traveling with speed 1.0x104 m/s. The magnetic field has strength 0.10 T. What is the magnitude of the charge of particle 3? (a) 1.0x10-8 C (b) 1.0 μC (c) 1.0 nC (d) 1.0x10-9 A Physics 112 N Midterm Exam A 1.0 cm I = 0.10 A 1 2 3 [ Show working ] [4 points] [6 points] [ Show working ] 8 Shown is a ray passing between a medium of refractive index 1.50 and another of unknown refractive index. What is the refractive index of medium 2? What is the critical angle for total internal reflection for light within medium 1? Complete the ray started in the diagram, labeling its angle with respect to the normal What is the speed of light in medium 1 ? Physics 112 N Midterm Exam n!=1.50 n" 60 º n!=1.50 n" 40 º 60 º [10 points] 9 An object of height 2.00 cm is placed 3.00 m from the vertex of a concave spherical mirror whose radius of curvature has absolute value 1.00 m. What is the focal length of this mirror? Label the focal point on the diagram below. Add sufficient principal rays to the diagram to (graphically, not numerically) determine the position and size of the image. Using appropriate equations determine numerical values for the position and size of the image. Sign conventions are given on the front of this booklet. Is the image real? (a) Yes (b) No Is it upright? (a) Yes (b) No Physics 112 N Midterm Exam C NOT TO SCALE The object and the center of curvature are already labelled Would the image appear on a screen placed at the image position? (a) Yes (b) No [13 points] 10 A circular loop of conducting wire of radius 1.20 cm is at rest in uniform magnetic field of magnitude 1.60 T . The plane of the loop is perpendicular to the direction of the magnetic field. What is the magnetic flux through the loop? What is the induced emf in the loop? The magnetic field strength is reduced uniformly from 1.60 T to zero in 0.10 s. What is the induced emf in the loop? The wire has resistance 3.62 mΩ. What is the induced current in the wire? Use Lenz’s law to determine the direction of the induced current. Is it (a) clockwise (b) counter-clockwise as viewed in the diagram above ? Physics 112 N Midterm Exam [10 points]