Physics Exam 3 Tested Questions with Accurate Answers Guaranteed to get an A (2025 Version).

Physics Exam 3 Tested Questions with Accurate Answers Guaranteed to get an A (2025 Version). You stand near the edge of a swimming pool and observe through the water an object lying on the bottom of the pool. Which of the following statements correctly describes what you see? The apparent depth of the object is less than the real depth. In the evening you go back to the swimming pool with your friends. The object is still lying on the bottom of the pool in the same location as before, but since it's dark now, you use a flashlight to show it to your friends. Remembering the apparent location of the object in daylight, where should you aim to illuminate the object with the flashlight? Assume you hold the flashlight at eye level. You should aim the flashlight at the same location as that of the apparent image seen in daylight. The picture shows a light ray passing from glass into water. Which of the following choices A-D represents the ray within the water? A (the highest ray) You look down into an aquarium tank filled with water and observe a small fish apparently in the position shown in the picture. Which of the labels A−D show the most likely actual position of the fish? B (the one right below the fish) When light propagates from a material with a given index of refraction into a material with a smaller index of refraction, the speed of the light increases What is the minimum value that the index of refraction can have? +1 Now consider a ray of light that propagates from water (n=1.33) to air (n=1). If the incident ray strikes the water-air interface at an angle θ1≠0, which of the following relations regarding the angle of refraction, θ2, is correct? θ2 θ1 Consider a ray of light that propagates from water (n=1.33) to glass (n=1.52). If the incident ray strikes the water-glass interface at an angle θ1≠0, which of the following relations regarding the angle of refraction θ2 is correct? θ2 θ1 Consider a ray of light that propagates from air (n=1) to any one of the materials listed below. Assuming that the ray strikes the interface with any of the listed materials always at the same angle θ1, in which material will the direction of propagation of the ray change the most due to refraction? diamond (n=2.417) In the case of n1n2, if the incidence angle is increased, the angle of refraction increases up to a maximum value of 90 degrees. What is the critical angle θcrit for light propagating from a material with index of refraction of 1.50 to a material with index of refraction of 1.00? 0.730 radians (sin theta = 1/1.5) He-Ne lasers are often used in physics demonstrations. They produce light of wavelength 633 nm and a power of 0.900 mW spread over a cylindrical beam 1.35 mm in diameter (although these quantities can vary). What is the intensity of this laser beam? 629 W/m2 What is the maximum value of the electric field? 688 V/m What is the maximum value of the magnetic field? 2.29 μT What is the average energy density in the laser beam? 2.10×10−6 J/m3 A plane electromagnetic wave is traveling vertically downward with its magnetic field pointing northward. Its electric field must be pointing toward the west. Which of the following statements about radio waves, infrared radiation, and x rays are correct? (There may be more than one correct choice.) A. They all have the same wavelength in vacuum. B. They all have the same frequency in vacuum. C. They all have exactly the same speed as visible light in vacuum. D. The short-wavelength x rays travel faster through vacuum than the long-wavelength radio waves. C A dentist's mirror is 2.0 cm from a tooth. The image is located 6.0 cm behind the mirror and is enlarged. What kind of mirror is being used? Concave mirror What is the focal length of the mirror? 3.0 cm What is the magnification of the mirror? +3 How is the image relative to the object? The image is upright A concave mirror has a radius of curvature R=20cm. An object of height 2 cm is placed 15 cm in front of the mirror. What is the image distance? 30 cm What is the height of the image? -4.0 cm You want to install the shortest possible wall mirror that will let you see all of yourself when you stand straight. The bottom edge of the mirror must be halfway between the floor and your eyes One of your friends was playing with a mirror and tells you that he created a real, inverted image that was larger than the object he was holding in front of the mirror. What type of mirror was your friend playing with? A concave mirror A "biconvex" lens is one in which both surfaces of the lens bulge outwards. Suppose you had a biconvex lens with radii of curvature with magnitudes of |R1|=10cm and |R2|=15cm. The lens is made of glass with index of refraction nglass=1.5. We will employ the convention that R1 refers to the radius of curvature of the surface through which light will enter the lens, and R2 refers to the radius of curvature of the surface from which light will exit the lens. Is this lens converging or diverging? converging What is the focal length f of this lens in air (index of refraction for air is nair=1)? 12 cm What is the focal length of the lens if it is immersed in water (nwater=1.3)? 39 cm Two plane mirrors intersect at right angles. A laser beam strikes the first of them at a point d=9.00cm from their point of intersection, as shown in (Figure 1). For what angle of incidence at the first mirror will this ray strike the midpoint of the second mirror (which is s=27.2cm long) after reflecting from the first mirror? 33.5 degrees A light beam travels at 1.94×108 m/s in quartz. The wavelength of the light in quartz is 355 nm. What is the index of refraction of quartz at this wavelength? 1.55 If this same light travels through air, what is its wavelength there? 549 You (height of your eyes above the water, h = 1.70 m ) are standing 2.00 m from the edge of a 2.50-m-deep swimming pool (Figure 1). You notice that you can barely see your cell phone, which went missing a few minutes before, on the bottom of the pool. The index of refraction of water at this temperature is 1.333. How far from the side of the pool is your cell phone? 1.74 A plate of glass with parallel faces having a refractive index of 1.53 is resting on the surface of water in a tank. A ray of light coming from above in air makes an angle of incidence 36.0 ∘ with the normal to the top surface of the glass. What angle θ3 does the ray refracted into the water make with the normal to the surface? Use 1.33 for the index of refraction of water 26.2 degrees What is the wavelength λ of light in glass, if its wavelength in air is λ0, its speed in air is c, and its speed in the glass is v? λ0v/c The index of refraction n for a material is defined to be n=c/v. Rewrite your answer from Part A in terms of the index of refraction. λ0/n If red light of wavelength 700 nm in air enters glass with index of refraction 1.5, what is the wavelength λ of the light in the glass? 467 nm If light strikes the air/glass interface at an angle 32.0 degrees to the normal, what is the angle of reflection, θr? 32 degrees If light strikes the air/glass interface at an incidence angle of 32.0 degrees, what is the angle of refraction, θb? Use 1.50 for the index of refraction of glass. 20.7 Light enters a solid tube made of plastic having an index of refraction of 1.64. The light travels parallel to the upper part of the tube. (See (Figure 1).) You want to cut the face AB so that all the light will reflect back into the tube after it first strikes that face. What is the largest that θ can be if the tube is in air? 52.4 degrees We have an expert-written solution to this problem! If the tube is immersed in water of refractive index 1.33, what is the largest that θ can be? 35.8 degrees The following are positioned in sequence: A source of a beam of natural light of intensity I0; three ideal polarizers A, B, and C; and an observer. Polarizer axis angles are measured clockwise from the vertical, from the perspective of the observer. The axis angle of polarizer A is set at zero degrees (vertical), and the axis angle of polarizer C is set at 50 degrees. In the situation above, polarizer B is set so that the beam intensity is zero at the observer. The two possible axis angle settings of polarizer B are: 90 and 140 Physicians use high-frequency (f=1MHz to 5MHz) sound waves, called ultrasound, to image internal organs. The speed of these ultrasound waves is 1480 m/s in muscle and 344 m/s in air. We define the index of refraction of a material for sound waves to be the ratio of the speed of sound in air to the speed of sound in the material. Snell's law then applies to the refraction of sound waves. At what angle from the normal does an ultrasound beam enter the heart if it leaves the lungs at an angle of 9.75 ∘ from the normal to the heart wall? (Assume that the speed of sound in the lungs is 344 m/s .) 46.8 What is the critical angle for sound waves in air incident on muscle? 13.4 Some insect eyes have two types of cells that are sensitive to the plane of polarization of light. In a simple model, one cell type (type H) is sensitive to horizontally polarized light only, and the other cell type (type V) is sensitive to vertically polarized light only. To study the responses of these cells, researchers fix the insect in a normal, upright position so that one eye is illuminated by a light source. Then several experiments are carried out. First, light with a plane of polarization at 45∘ to the horizontal shines on the insect. Which statement is true about the two types of cells? Both types detect this light We have an expert-written solution to this problem! The near point (the smallest distance at which an object can be seen clearly) and the far point (the largest distance at which an object can be seen clearly) are measured for six different people. Which, if any, of these people are nearsighted (myopic)? BCE Which, if any, of these people require bifocals to correct their vision? BE Which, if any, of these people's vision can be corrected using only converging lenses? AF Of the farsighted people, rank them by the power of the lens needed to correct their hyperopic vision. E F A B A certain lens forms a real image of a very distant object on a screen that is 10 cm from the lens. As the object is moved closer to the lens, at what distance of the object from the lens are the object and the image the same height? Only at 20 cm A lens projects an image onto a screen. If the left half of the screen is covered, then the image becomes fainter Suppose you are looking through a magnifier with a focal length of f, but you want to see the object you are looking at with an even greater angular magnification. Which new magnifier should you choose to enlarge the object even more? A magnifier with a shorter focal length A single-slit diffraction pattern is formed on a distant screen. If the width of the single slit through which light passes is reduced, what happens to the width of the central bright fringe? Assume the angles involved remain small. The central bright fringe becomes wider