3PhysicsPracticeTest

Test 3 PHY 102 Fall 2022 “On my honor, I have neither received nor given aid on this examination” Name: ID:_ ___________________ Signature: Check the discussion session [ ] 4C: 10:10AM – 11:00AM [ ] 4D: 11:15AM – 12:05PM [ ] 4E: 12:20PM – 1:10PM [ ] 4F: 1:25PM – 2:15PM Attempt all problems. The exam include 16 multiple-choice and 2 open response questions. Marking more than one answer for multiple choice questions results zero to that question. This is a closed book exam, you must work independently! No collaboration is allowed. Prohibited items: any electronic devices including cell phones, notes and books. You can have pencil, eraser, and calculator. Anyone found cheating during the exam will automatically receive an “F” grade for the course and sent to the honor’s court.

1. (5 points) An object is placed 10 cm from a convex lens of focal length 20 cm. What is the magnification? A. 0.50 B. 1.0 C. 1.25 D. 1.50 E. 2.0 2. (5 points) A concave mirror produces a real image that is three times as large as the object. If the object is 20 $% in front of the mirror, what is the focal length of the mirror? A. 60 cm B. 45 cm C. 30 cm D. 15 cm E. 10 cm 3. (5 points) A person needs glasses with a refractive power of -1.38 diopters to be able to focus on distant objects. What is this person's (unaided) far point? A. 72.5 cm B. 23.0 cm C. 112 cm D. 101 cm E. 54.2 cm 4. (5 points) Diego is nearsighted and cannot see things beyond 110 cm from his eyes. What is the focal length of the contact lenses that will enable him to comfortably see distant hills clearly? A. +110 cm B. -110 cm C. +50 cm D. -50 cm E. -30 cm 5. (5 points) Assuming a pupil diameter of 3 mm, what is the angular resolution of the human eye for light at the middle of the visible spectrum (550 nm)? A. 0.8° B. 0.2° C. 0.01° D. 2° E. 5°

10. (5 points) A beam of light, traveling in air, strikes a plate of transparent material at an angle of incidence of 56.0°. It is observed that the reflected and refracted beams form an angle of 90.0°. What is the index of refraction of this material? A. 1.40 B. 1.43 C. 1.44 D. 1.48 E. 1.50 11. (5 points) A prism of glass has two angles of 45 ° and one of 90 ° . To determine the index of refraction of the glass in this prism, an experimenter aims a beam of light perpendicularly into a face of this prism and measures the angle at which the ray emerges on the far side. If this angle is 72 ° , what is the index of refraction? A. 1.10 B. 1.34 C. 1.42 D. 1.50 E. 1.61 12. (5 points) A metal has a work function of 4.50 eV. Find the maximum kinetic energy of the photoelectrons if light of wavelength 250 nm shines on the metal. (1 eV = 1.60 × 10 -19 J, c = 3.00 × 10 8 m/s, h = 6.626 × 10 -34 J ∙ s) A. 0.00 eV B. 0.37 eV C. 0.47 eV D. 0.53 eV E. 0.67 eV 13. (5 points) In Compton scattering from stationary electrons the largest change in wavelength occurs when the photon is scattered through: A. 180 0 B. 90 0 C. 60 0 D. 30 0 E. 0

14. (5 points) Suppose a blackbody with a surface temperature of 5800 3 radiates electromagnetic energy. At what wavelength does the object emit most strongly? ( $ = 3 × 10 ! %/, ) A. 879 nm B. 422 nm C. 537 nm D. 698 nm E. 758 nm 15. (5 points) If the wavelength of a photon is doubled, what happens to its energy? A. It stays the same. B. It is reduced by one-fourth. C. It is doubled. D. It is halved. E. It is quadrupled. 16. (5 points) Gamma rays are photons with very high energy. How many visible-light photons with a wavelength of 500 nm would you need to equal the energy of a gamma- ray photon with energy ( c = 3.00 × 10 8 m/s, h = 6.626 × 10 -34 J ∙ s) A. 1.4 × 10 8 B. 6.2 × 10 9 C. 3.9 × 10 3 D. 3.9 × 10 10 E. 1.0 × 10 6 17. (10 points) A concave mirror reflects an image of the Moon ( 6 " → ∞ ) at 6.0 cm from the mirror. If a coin is placed 8.0 cm from the same mirror, where will its image be? (Show your work in detail)

Mirrors and lenses: Mirror and lens equation: # $ ! + # $ " = # % and : = & ' Magnification: % = − $ ! $ " For concave mirrors: : > 0 and for convex mirrors : < 0 For concave lens (diverging lens) : < 0 and for convex lens (Converging lens) : > 0 Eyes: For nearsighted eyes: use diverging lenses ( : < 0) For farsighted eyes: use converging lenses ( : > 0) Refraction: @ = $/* A ( = A/* Snell’s law: * # ,)*B # = * ' ,)*B ' critical angle: ,)*B ) = * ' /* # Brewster’s angle: CD*B * = * ' /* # refractive power= 1/: Young two slit experiment: 6,)*B + = %A % = 0, ±1, ±2, … for constructive interference 6,)*B $ = H% ± # ' I A % = 0,1,2, … for destructive interference Single slit diffraction: The condition for dark points: J,)*B $ = %A % = ±1, ±2, … Where J is the with of the slit. Resolution in Circular Aperture: B ,-( = 1.22 A/K Diffraction grating: 6,)*B + = %A % = 0, ±1, ±2, … Quantum Mechanics: Electromagnetic waves: $ = A: where c in vacuum is $ = 3 × 10 ! %/, Wien’s displacement law: : ./01 = (5.88 × 10 #" , 2# 3 2# )L Energy of photon: M = *ℎ: , momentum of a photon: O = ℎ/A Photoelectric effect: ℎ: = J + 3M Compton scattering: ΔA = 3 , # ) ( 1 − $Q,B) where B is scattering angle of photon. De Broglie wavelength: A = ℎ/O