AP Physics 2 Unit 6 MCQ B

The figure above shows a close-up view of a piece of plastic in air. The thickness of the plastic varies slightly, as shown. Monochromatic light strikes nearly perpendicular to the upper surface of the plastic. A person above the plastic sees two bright bands of the light at the positions on the plastic where its thickness is x1 and x2. Rays of light are also shown that illustrate typical reflected and refracted rays for any location. Which of the following conditions are directly related to the formation of these bright bands? Select two answers.

B + C. At each location, rays A and B are in phase so they interfere constructively / Thicknesses x1 and x2 are some multiple of half the wavelength of the light in the plastic.

During an experiment, a group of students must determine the critical angle of a plastic prism. Each student shines a laser beam through the plastic prism, as shown in the figure, and adjusts the angle θ1θ1 of the incident beam until the beam leaving the flat face of the prism lies along the plastic-air boundary. Each student measures the angle θ1θ1. The students' measurements of the critical angle do not agree, as shown in the table. Which of the following methods could give the students values for the critical angle that would more likely show better agreement? Select two answers.

B + D. Each student could repeat the described procedure multiple times and average the measurements / Each student could take measurements of θ2 for multiple values of θ1, graph sinθ2 as a function of sinθ1, and draw a best-fit line. The point on the line for which sinθ2=1 will give the value of sinθ1 for the critical angle.

An electromagnetic wave propagates in the y-direction and the magnetic field oscillates parallel to the x-axis. The wavelength of the wave is 25nm and the amplitude of the oscillation is 0.0015T. Which of the following equations best describes the magnetic field as a function of time at a particular position?

B. (0.015T)cos[2π(1.2×1016Hz)t]

Two lasers, X and Y, shine light of the same frequency onto a single point P on a screen. The graphs above show the electric field of the light wave from each laser at point P as a function of time. What is the amplitude of the resulting wave at point P?

B. 0.5 N/C

A salesperson is sometimes working at the location shown in the floor plan above when customers enter a store. In order to be able to see the customers enter the door at the position shown, the salesperson wants to hang a plane mirror on the indicated wall. In which labeled section of the wall should the mirror be hung to enable the salesperson to see the customers?

B. B (second from the top)

A beam of monochromatic light in material A enters material B, which has a higher index of refraction than material A. How do the speed, frequency, and wavelength of the light in material B compare to those in material A?

C. Smaller; Shorter; The same

A narrow beam of monochromatic light is incident on the surface of a block of glass, creating reflected and refracted beams. Which of the following must be true of the beams?

C. The sum of the intensities of the reflected and refracted beams is less than or equal to the intensity of the incident beam.

A student must design an experiment and data analysis procedure that will determine the index of refraction nglass of a type of glass. The student will shine a ray of light from air into the glass, as shown in the ray diagram. Which procedure and data analysis method could be used to determine the index of refraction nglass?

C. Vary the angle θ2 to several different values. Measure the resulting value of θ3. Create a graph with sinθ2 as the vertical axis and sinθ3 as the horizontal axis. A graph of the data will be linear with a slope equal to the index of refraction nglass of the glass.

An object is placed between a concave mirror and its focal point, as shown in the figure. The resulting image will be

C. Virtual and Upright

The graphs show the electric field E of two waves as functions of position xx, both of which are cosine curves with amplitudes Emax. Which of the following claims best describes the net field due to the overlap of the two waves?

D. A curve that is neither a cosine or a sine curve and is not symmetric about the xx-axis

In an experiment to determine the index of refraction of a piece of glass, students shine a laser beam on the glass at several different angles to the normal between 0° and 90°. For each angle of incidence, they record the angle of refraction of the laser beam in the glass. Which of the following is the best procedure the students can use to determine the index of refraction of the glass?

D. Calculate the slope of the best-fit line to a graph of the sine of the angle of incidence as a function of the sine of the angle of refraction

A student places two materials into contact. Material 1 has known index of refraction n1 and material 2 has unknown index of refraction n2. The student directs a laser beam through the materials and measures the incident angle θ1 in material 1 and the refracted angle θ2 in material 2. The data are given in the table. The student concludes that the index of refraction of material 2 is greater than the index of refraction of material 1. Is the student's conclusion reasonable, and why or why not?

D. The conclusion is reasonable because for most of the data, θ1 is greater than θ2.

Which of the following claims best describes what happens to the intensity of light when it is incident on a clear glass window?

D. The sum of the intensities of the reflected and transmitted light must be less than the intensity of the incident light.

Which of the following equations describes the wave shown in the graph?

D. x(t)=2cos(π2t)

Two pulses on a rope move toward each other at the same speed. Each pulse has the width and amplitude shown in the figure above. Which of the following show the shape of the rope at some time after the instant shown above? Select two answers.

A + C. One with downward hump at y=0 and the inverse of the original graph

A child is using a wand like the one shown to create soap bubbles. The child notices that when the wand is held still for a short time colored bands appear in the soap film. Which of the following processes are involved in the formation of these colored bands? Select two answers.

A + C. Superposition / Reflection

The figure above shows white light in air with an index of refraction na=1.0. The light strikes a thin film of oil (no=1.8) that is coating a piece of glass (ng=1.5). A person looking down at the glass sees blue light of wavelength 425 nm coming from the location of the dot. The minimum possible thickness of the oil is most nearly

A. 59 nm