MCAT physics chap 8 light/optics 14%
electromagnetic waves
" are transverse waves because the oscillating electric and magnetic field vectors are perpendicular to the direction of propagation. The electric field and the magnetic field are also perpendicular to each other. " Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
spherical aberration
" blurring of the periphery of an image as a result of inadequate reflection of parallel beams at the edge of a mirror or inadequate refraction of parallel beams at the edge of a lens. This creates an area of multiple images with very slightly different image distances at the edge of the image, which appears blurry." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
diffreacting gratings
" consist of multiple slits arranged in patterns. Diffraction gratings can create colorful patterns similar to a prism as the different wavelengths interfere in characteristic patterns. For example, the organization of the grooves on a CD or DVD act like a diffraction grating, creating an iridescent rainbow pattern on the surface of the disc. " Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
chromatic aberration
" dispersive effect within a spherical lens. Depending on the thickness and curvature of the lens, there may be significant splitting of white light, which results in a rainbow halo around images. This phenomenon is corrected for in visual lenses like eyeglasses and car windows with special coatings that have different dispersive qualities from the lens itself." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
converging and diverging lenses
" illustrates that a converging lens is always thicker at the center, while Figure 8.11b illustrates that a diverging lens is always thinner at the center. The basic formulas for finding image distance and magnification for spherical mirrors also apply to lenses. The object distance o, image distance i, focal length f, and magnification m, are related by the equations and " Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
image distance
" image distance for all types of mirrors and lenses. If the image has a positive distance (i > 0), it is a real image, which implies that the image is in front of the mirror. If the image has a negative distance (i < 0), it is virtual and thus located behind the mirror. Plane mirrors can be thought of as spherical mirrors with infinitely large focal distances. As such, for a plane mirror, r = f = ∞, and the equation becomes or i = -o. This can be interpreted as saying the virtual image is at a distance behind the mirror equal to the distance the object is in front of the mirror." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
units of wavelengths
" mm (10-3 m), µm (10-6 m), nm (10-9 m), and Å (ångström, 10-10 m). The full spectrum is broken up into many regions, which in descending order of wavelength are radio (109-1 m), microwave (1 m-1 mm), infrared (1 mm-700 nm), visible light (700-400 nm), ultraviolet (400-50 nm), x-ray (50-10-2 nm), and γ-rays (less than 10-2 nm)." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
critical angle
"As the incident angle is increased, the refracted angle also increases, and eventually, a special incident angle called the critical angle (θc) is reached, for which the refracted angle θ2 equals 90 degrees. At the critical angle, the refracted light ray passes along the interface between the two media. The critical angle can be derived from Snell's law if θ2 = 90°, such that " θc= sin-1 (n2/n1)
key concept mirrors and lenses
"Concave mirrors are converging mirrors. Convex mirrors are diverging mirrors. The reverse is true for lenses." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
real world lenses
"Converging lenses (reading glasses) are needed by people who are "farsighted." Diverging lenses (standard glasses) are needed by people who are "nearsighted." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
diffraction
"Diffraction refers to the spreading out of light as it passes through a narrow opening or around an obstacle. Interference between diffracted light rays lead to characteristic fringes in slit-lens and double-slit systems. Diffraction and interference are significant evidence for the wave theory of light." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"How does the diffraction pattern for a single slit differ from a slit with a thin lens?" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Diffraction through a single slit does not create characteristic fringes when projected on a screen, although the light does spread out. When a lens is introduced into the system, the additional refraction of light causes constructive and destructive interference, creating fringes." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Define the following terms: Dispersion: Aberration:" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Dispersion is the tendency for different wavelengths of light to experience different degrees of refraction in a medium, leading to separation of light into the visible spectrum (a rainbow). Aberration (spherical or chromatic) is the alteration or distortion of an image as a result of an imperfection in the optical system." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"True or False: Light waves are longitudinal because the direction of propagation is perpendicular to the direction of oscillation." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"False. Light waves are transverse because the direction of propagation is perpendicular to the direction of oscillation." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
convex surface
"For a convex surface, the center of curvature and the radius of curvature are behind the mirror" diverging mirror cause parallel incident light rays to converge and diverge after they reflect
real lenses and lensmaker's eq
"For lenses where the thickness cannot be neglected, the focal length is related to the curvature of the lens surfaces and the index of refraction of the lens by the lensmaker's equation:" 1/f= (n-1) (1/r1- 1/r2)
"What wave phenomenon do diffraction fringes result from?" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Fringes result from constructive and destructive interference between light rays" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
snells law and n
"From Snell's law, we can see that when light enters a medium with a higher index of refraction (n2 > n1), it bends toward the normal (sin θ2 < sin θ1; therefore, θ2 < θ1), as shown in Figure 8.9. Conversely, if the light travels into a medium where the index of refraction is smaller (n2 < n1), the light will bend away from the normal (sin θ2 > sin θ1; therefore, θ2 > θ1)." when n2>n1, bends toward dotted line going straight down opposite is true
color prism
"If a source of white light is incident on one of the faces of a prism, the light emerging from the prism is spread out into a fan-shaped beam, as shown in Figure 8.13. This occurs because violet light has a smaller wavelength than red light and so is bent to a greater extent. Because red experiences the least amount of refraction, it is always on top of the spectrum; violet, having experienced the greatest amount of refraction, is always on the bottom of the spectrum. Note that as light enters a medium with a different index of refraction, the wavelength changes but the frequency of the light does not." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
mnenomic single lens mirrors
"Image types with a single lens or mirror (assuming o is positive): UV NO IR Upright images are always virtual No image is formed when the object is a focal length away Inverted images are always real" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
real images and virtual images of plane mirrors
"In general, images created by a mirror can be either real or virtual. An image is said to be real if the light actually converges at the position of the image. An image is virtual if the light only appears to be coming from the position of the image but does not actually converge there. One of the distinguishing features of real images is the ability of the image to be projected onto a screen." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
colors and refraction
"Light that contains all the colors in equal intensity is perceived as white. The color of an object that does not emit its own light is dependent on the color of light that it reflects. Thus, an object that appears red is one that absorbs all colors of light except red. This implies that a red object under green illumination will appear black because it absorbs the green light and has no light to reflect. The term blackbody refers to an ideal absorber of all wavelengths of light, which would appear completely black if it were at a lower temperature than its surroundings." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Describe the bending of light when moving from a medium with low refractive index to high refractive index, and from a medium with high refractive index to low refractive index: Low n to high n: High n to low n:" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Light will bend toward the normal when going from a medium with low n to high n. Light will bend away from the normal when going from a medium with high n to low n; if the incident angle is larger than the critical angle (θc), total internal reflection will occur." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"A penny sits at the bottom of a pool of water (n = 1.33) at a depth of 3.0 m. If an observer 1.8 m tall stands 30 cm away from the edge, how close to the side can the penny be and still be visible?" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Note that the light is coming from the water (n1 = 1.33) and going into the air (n2 ≈ 1), so the light is bent away from the normal (θ2 > θ1). We need to find the angle that the light rays make with the normal to the water's surface:" "Note that you will not be expected to calculate precise values of trigonometric functions or inverse trigonometric functions on Test Day. This question is provided mainly as an opportunity to see the application of Snell's law." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
thin spherical lenses
"On the MCAT, lenses generally have negligible thickness. Because light can travel from either side of a lens, a lens has two focal points, with one on each side. The focal length can be measured in either direction from the center. For thin spherical lenses, the focal lengths are equal, so we speak of just one focal length for the lens as a whole." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"How does the application of a polarized filter impact the wavelength of light passing through the filter?" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Plane polarization has no effect on the wavelength (or frequency or speed) of light. Polarization does affect the amount of light passing through a medium and light intensity." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Contrast plane-polarized and circularly polarized light:" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Plane-polarized light contains light waves with parallel electric field vectors. Circularly polarized light selects for a given amplitude and has a continuously rotating electric field direction." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
reflection
"Reflection is the rebounding of incident light waves at the boundary of a medium. Light waves that are reflected are not absorbed into the second medium; rather, they bounce off of the boundary and travel back through the first medium" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
refraction
"Refraction is the bending of light as it passes from one medium to another and changes speed. The speed of light through any medium is always less than its speed through a vacuum. Remember that the speed of light in a vacuum, c, is equal to 3e8 The speed of light in air is just slightly lower that this value; on the MCAT, it is appropriate to use for the speed of light in air." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
key concept bending light
"Remember that when light enters a medium with a higher index of refraction, it bends toward the normal. When light enters a medium with a lower index of refraction, it bends away from the normal." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
sign conventions for mirror varibles
"Symbol Positive Negative o Object is in front of mirror Object is behind mirror (extremely rare) i Image is in front of mirror (real) Image is behind mirror (virtual) r Mirror is concave (converging) Mirror is convex (diverging) f Mirror is concave (converging) Mirror is convex (diverging) m Image is upright (erect) Image is inverted" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
sign convention for lenses
"Symbol Positive Negative o Object is on same side of lens as light source Object is on opposite side of lens from light source (extremely rare) i Image is on opposite side of lens from light source (real) Image is on same side of lens as light source (virtual) r Lens is convex (converging) Lens is concave (diverging) f Lens is convex (converging) Lens is concave (diverging) m Image is upright (erect) Image is inverted" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"From the previous example, suppose another penny is 3 m away from the edge. Will a light ray going from this penny to the edge of the pool emerge from the water?" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"The angle made by the second penny's light ray is Find the critical angle: It is not expected on the MCAT that we know the inverse sin of 0.75. However, we do know that Since sin (θc) is greater than 0.71, the critical angle must be greater than 45°. Therefore, θc > θ1 and the light ray will emerge from the pool." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
center of curvature and radius of curvature
"The center of curvature is a point on the optical axis located at a distance equal to the radius of curvature from the vertex of the mirror; in other words, the center of curvature would be the center of the spherically shaped mirror if it were a complete sphere." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
slit lens system
"The central bright fringe (maximum) is twice as wide as the bright fringes on the sides, and as the slit becomes narrower, the central maximum becomes wider. The location of the dark fringes (minima) is given by the formula a sin θ = nλ " "where a is the width of the slit, θ is the angle between the line drawn from the center of the lens to the dark fringe and the axis of the lens, n is an integer indicating the number of the fringe, and λ is the wavelength of the incident wave. Note that bright fringes are halfway between dark fringes." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
key concept unpolarized light
"The electric fields of unpolarized light waves exist in all three dimensions: the direction of the wave's propagation is surrounded by electric fields in every plane perpendicular to that direction. Polarizing light limits the electric field's oscillation to only two dimensions." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
key concept focal length
"The focal length of converging mirrors (and converging lenses) will always be positive. The focal length of diverging mirrors (and diverging lenses) will always be negative." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"An object is 15 cm to the left of a thin diverging lens with a 45 cm focal length as shown below. Find where the image is formed, if it is upright or inverted, and if it is real or virtual. What is the radius of curvature, assuming the lens is symmetrical and is made of glass with a non negligible thickness and an index of refraction of 1.50?" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"The image distance (i) is found using the equation 1/f = 1/o + 1/i -> 1/i= 1/f=1/o Because the lens is diverging, the focal length has a negative sign (f = −45 cm). The object, like any object in a single-lens system, has a positive sign (o = +15 cm). Now we can solve for i: 1/i= 1/f-1/o=1/-45 - 1/15= /4/45= -11.25 The negative sign indicates that the image is on the same side of the light source and is virtual. Remember that for a single lens or mirror, virtual images are always upright. The thickness of a lens is usually negligible, but we are told otherwise in this question. To determine the radii of curvature, we use the lensmaker's equation. Because the lens is symmetrical, the radii are equal but opposite in sign. As the light progresses from left to right, the first surface of the lens is concave (r1 < 0), and the second surface of the lens is convex (r2 > 0). 1,f= n-1 (1/r1 -1/r2= (n-q) (-1/r-1/r)= (n-1)(-2/r) r= -2f(n-1) = -2(-45)(1.5-1)= 2(45)(.5)= 45 cm
"How does double-slit diffraction and interference differ from single-slit diffraction?" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"The image formed during double-slit diffraction contains fringes because light rays constructively and destructively interfere. A single slit forms an image of a wide band of light, spread out from its original beam" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
real world mirror
"The passenger-side mirrors in cars are an example of convex mirrors (everything appears smaller and farther away); the small circular mirrors used for applying makeup are an example of concave mirrors (everything appears bigger and closer)." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
lenses
"There is an important difference between lenses and mirrors, aside from the fact that lenses refract light while mirrors reflect it. When working with lenses, there are two surfaces that affect the light path. For example, a person wearing glasses sees light that travels from an object through the air into the glass lens (first surface). Then the light travels through the glass until it reaches the other side, where again it travels out of the glass and into the air (second surface). The light is refracted twice as it passes from air to lens and from lens back to air." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
key concept convex mirrors
"To find where the image is (for a mirror), draw the following rays and find a point where any two intersect. This point of intersection marks the tip of the image. If the rays you draw do not appear to intersect, extend them to the other side of the mirror, creating a virtual image." "Ray parallel to axis → reflects back through focal point Ray through focal point → reflects back parallel to axis Ray to center of mirror → reflects back at same angle relative to normal" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
total internal reflection key concept
"Total internal reflection occurs as the light moves from a medium with a higher refractive index to a medium with a lower one." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"True or False: Incident angle is always measured with respect to the normal." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"True. In optics, incident angles are always measured relative to the normal." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"True or False: Maxima in diffraction patterns are always equidistant between two minima." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"True. Maxima and minima alternate in a diffraction pattern. A maximum is equidistant between two minima, and a minimum is equidistant between two maxima." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
unpolarized light
"Unpolarized light has a random orientation of its electric field vectors; sunlight and light emitted from a light bulb are prime examples. " Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"An object is placed 6 cm in front of a concave mirror that has a 10 cm radius of curvature. Determine the image distance, the magnification, whether the image is real or virtual, and whether it is inverted or upright. " Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Use the optics equation: 1/f= 1/o + 1/i = 2/r 1/i= 2/r -1/o 1/i= 2/10 -1/6= 1/30 30/1= i=+30 A positive value for i signifies that the image is in front of the mirror and is therefore real. For a single lens or mirror with o > 0, a real image will always be inverted. After determining i , the magnification m can be calculated as: m= -i/o= -30/6= -5 The negative sign on the magnification confirms that the image is inverted, and the fact that |m| > 1 indicates that the image is enlarged." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"What are the boundaries of the visible spectrum? How does the range of the visible spectrum compare to the range of the " Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Visible light ranges from wavelengths of about 400 nm to 700 nm. This is in comparison to the entire EM spectrum which ranges from wavelengths of nearly 0 to 109 m." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
rectilinear propagation
"When light travels through a homogeneous medium, it travels in a straight line. This is known as rectilinear propagation. The behavior of light at the boundary of a medium or interface between two media is described by the theory of geometrical optics. Geometrical optics explains reflection and refraction, as well as the applications of mirrors and lenses." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
dispersion
"When various wavelengths of light separate from each other, this is called dispersion. The most common example of dispersion is the splitting of white light into its component colors using a prism." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
multiple slits
"When waves interact with each other, the displacements of the waves add together in a process called interference" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
x-ray diffraction
"X-ray diffraction uses the bending of light rays to create a model of molecules. X-ray diffraction is often combined with protein crystallography during protein analysis. Dark and light fringes do not take on a linear appearance, but rather a complex two dimensional image." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
total interanl reflection
"a phenomenon in which all the light incident on a boundary is reflected back into the original material, results with any angle of incidence greater than the critical angle, θc," "At the incident angle of θc, the refracted angle is equal to 90°; at incident angles above 90°, total internal reflection occurs." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
plane-polarized light
"is light in which the electric fields of all the waves are oriented in the same direction (that is, their electric field vectors are parallel). It follows that their magnetic fields vectors are also parallel, but convention dictates that the plane of the electric field identifies the plane of polarization" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Populate the following tables according to the sign conventions for mirrors and lenses:" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"o Object is in front of mirror Object is behind mirror (extremely rare) i Image is in front of mirror (real) Image is behind mirror (virtual) r Mirror is concave (converging) Mirror is convex (diverging) f Mirror is concave (converging) Mirror is convex (diverging) m Image is upright (erect) Image is inverted" "o Object is on same side of lens as light source Object is on opposite side of lens from light source (extremely rare) i Image is on opposite side of lens from light source (real) Image is on same side of lens as light source (virtual) r Lens is convex (converging) Lens is concave (diverging) f Lens is convex (converging) Lens is concave (diverging) m Image is upright (erect) Image is inverted" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
concave surface
"the center of curvature and the radius of curvature are located in front of the mirror. " converging mirror
"Order the types of electromagnetic radiation from highest energy to lowest energy. What other property of light follows the same trend?" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"γ-rays > x-rays > ultraviolet > visible light > infrared > microwaves > radio. Frequency follows the same trend as energy, whereas wavelength follows the opposite trend." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
multiple lenses eq
1/f= 1/f1 + 1/f2 + 1/f3... p= p1+p2+p3 m= m1xm2xm3
relationship between distances of concave mirror
1/f= 1/o + 1/i= 2/r make sure units are the same
"Monochromatic red light is allowed to pass between two different media. If the incident angle in medium 1 is 30° and the incident angle in medium 2 is 45°, what is the relationship between the speed of the light in medium 2 compared to that in medium 1?" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
A "First, the color of the light is irrelevant here; the ratio would be the same even if the specific color were not mentioned. Second, recall Snell's Law: n1 sin θ1 = n2 sin θ2. Although we don't know the value of n for either medium, you do know the simple relationshipn=c/v . Replacing n in Snell's law, and canceling out c from both sides, we get: c/v1 sin0= c/v2 sin02 sin30/v1= sin 45/v2 1/2v1= sq2/2v2 v2= v1sq2
"An object is placed at the center of curvature of a concave mirror. Which of the following is true about the image? It is real and inverted. It is virtual and inverted. It is real and upright. It is virtual and upright." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
A "One could solve this question with a ray diagram, but be wary about using ray diagrams on Test Day. It is easy to make small mistakes that cause the light rays not to intersect. Therefore, solve the question using the sign convention. If the object is at the center of curvature, its distance is 2f. We can plug into the optics equation: Because i is positive, the image is real. For single mirrors or lenses, all real images are inverted." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"A ray of light (f = 5 × 1014 Hz) travels from air into crystal into chromium. If the indices of refraction of air, crystal, and chromium are 1, 2, and 3, respectively, and the incident angle is 30°, then which of the following describes the frequency and the angle of refraction in the chromium? 5 × 1014 Hz; 9.6° 5 × 1014 Hz; 57° 1.0 × 1010 Hz; 9.6° 1.0 × 1010 Hz; 57°" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
A "This question contains two parts—we have to determine the frequency and the angle of refraction of the light ray. The first part, however, is straightforward because the frequency of a light ray traveling from one medium to another does not change. Because the frequency must be 5 × 1014 Hz, we can eliminate (C) and (D). For the angle of refraction, we can either calculate it or determine it using logic. First, the light ray goes from air into crystal; that is, from a low index of refraction to a higher one. According to Snell's law, the angle of refraction will be smaller than the incident angle (closer to the normal). When the light ray moves from crystal to chromium, it again goes from a lower index of refraction into a higher one, thus making the angle of refraction even smaller, eliminating (B). This question could also be answered by calculation using Snell's law, but the calculations are time consuming and unnecessary." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
normal
A line perpendicular to a surface boundary of the medium, all angles measured from the normal, not at surface of medium
"Which phenomenon would cause monochromatic light entering the prism along path AB to leave along path CD? Dispersion Refraction Diffraction Polarization" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
B "Even though the light is traveling through a prism, the change in the light's direction is caused by refraction, not dispersion. Dispersion involves the breaking up of polychromatic light into its component wavelengths because the degree of refraction depends on the wavelength. We are told that the incident light is monochromatic or, in other words, consists of only one wavelength; therefore, light will not be dispersed, eliminating (A). Diffraction, (C), describes the spreading of light waves as they pass through a small opening. Polarization, (D), is the alignment of the electric field component of light waves." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Which of the following describes the image formed by an object placed in front of a convex lens at a distance smaller than the focal length? Virtual and inverted Virtual and upright Real and upright Real and inverted" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
B "The image produced by a convex lens can be either real or virtual. It is real if the object is placed at a distance greater than the focal point, and virtual if the object is placed at a distance less than the focal point (between the focal point and the lens). Remember that for a single mirror or lens, an image that is real must be inverted and one that is virtual must be upright. In this question, the object is placed in front of the focal point, so the image must be virtual and, therefore, upright. We could also determine this from the optics equation. If f > o, then 1/f-1/o is negative, and i is therefore negative (virtual)." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"A child stands between two mirrors with his arms out, perpendicular to the mirrors. One plane mirror is 5 m away from his left hand and another plane mirror is 7 m away from his right hand. How far apart are the two images produced by the mirrors if the child has an arm span of 0.5 m? 2 m 12 m 12.5 m 24.5 m" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
B D "In plane mirrors, the image is as far away from the mirror as the object is. In other words, the image produced by the left mirror is 5 m away from the mirror because the child is standing 5 m away from the mirror. Similarly, the right mirror produces an image that is 7 m away from the center of the mirror. To calculate how far away the two images are, take into consideration not only the image distance but also the distance of the object (the child) from the mirrors and the child's arm span of 0.5 m. Therefore, the images are 5 + 5 + 0.5 + 7 + 7 = 24.5 m apart." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"If a light ray has a frequency of 5.0 × 1014 Hz, in which region of the electromagnetic spectrum is it located? X-ray UV Visible Infrared" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
BC "It is unnecessary to memorize the entire electromagnetic spectrum for Test Day; however, it is important to know that the visible spectrum runs from 400-700 nm. We can calculate the wavelength of this light ray:" speed of light= fw
"A student is analyzing the behavior of a light ray that is passed through a small opening and a lens and allowed to project on a screen a distance away. What happens to the central maximum (the brightest spot on the screen) when the slit becomes narrower? The central maximum remains the same. The central maximum becomes narrower. The central maximum becomes wider. The central maximum divides into smaller light fringes." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
C "This question is testing our understanding of diffraction. When light passes through a narrow opening, the light waves spread out; as the slit narrows, the light waves spread out even more. When a lens is placed between the narrow slit and the screen, a pattern consisting of alternating bright and dark fringes can be observed on the screen. As the slit becomes narrower, the central maximum (the brightest and most central fringe) becomes wider. This can also be seen in the equation for the position of dark fringes in a slit-lens setup (a sin θ = nλ). As a, the width of the slit, decreases, sin θ must increase because nλ is constant for a given fringe. If sin θ increases, θ necessarily increases, implying that the fringes are spreading farther apart." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"When monochromatic light is refracted as it passes from air to glass, which of the following does NOT remain the same? (Note: Assume that the wave is fully transmitted.) Wavelength Frequency Amplitude Period" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
C A "As light rays travel from one medium to another, their wavelengths change. Even if we did not know this immediately, we can determine the answer through process of elimination. Frequency and period are inverses of each other, so if either of these quantities changes, the other would have to change as well, eliminating (B) and (D). Further, because the wave is fully transmitted, there is no absorption or reflection, and the amplitude (which is related to intensity) should not change, eliminating (C). When light is refracted, its speed changes; although the frequency does not change, the wavelength does." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Which of the following are able to produce a virtual image? Convex lens Concave lens Plane mirror I only III only II and III only I, II, and III" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
D "All images produced by plane mirrors will be virtual, so statement III is true. The same goes for diverging species (convex mirrors and concave lenses), so statement II is true. Converging species (concave mirrors and convex lenses) can produce real or virtual images, depending on how far the object is from the species, so statement I is also true." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Imagine that a beam of monochromatic light originates in air and is allowed to shine upon the flat surface of a piece of glass at an angle of 60° with the normal. The reflected and refracted beams are perpendicular to each other. What is the index of refraction of the glass? 1 2 " Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
D "Drawing a diagram is best here. Because the angle given is with respect to the normal, you know that the incident angle must equal 60°. You know that the reflected beam will have an angle of 60° relative to the normal. Therefore, the reflected beam will make an angle of 30° with the plane of the glass. If the reflected and refracted beams are perpendicular to each other, the refracted beam will make a 60° angle with the plane of the glass. θrefracted is therefore 30° relative to the normal. Using n1 sin θ1 = n2 sin θ2, we have 1sin 60= n2 sin 30 sq3/2= n2 (1/2) sq3= n2 " Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"A scientist looks through a microscope with two thin lenses with m1 = 10 and m2 = 40. What is the overall magnification of this microscope? 0.25 30 50 400" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
D "The overall magnification of a system of multiple lenses is simply the product of each lens's magnification. In this case, that is 10 × 40 = 400." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"Which of the following will not result in the splitting of white light into its component colors? Dispersion through a prism Diffraction through a grating Refraction within a thin film Reflection from an ideal convex mirror" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
D "Light can be split into its component colors by dispersion, such as that through a prism, eliminating (A). Diffraction by a diffraction grating will also separate colors by their wavelengths, eliminating (B). The refraction of light within a thin film also leads to light dispersion as the different colors are refracted at slightly different angles in the film, eliminating (C). A mirror with significant aberration could lead to a separation of light into its component colors, but we are told that this is an ideal mirror. Thus, (D) is the correct answer." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"A source of light (f = 6.0 × 1014 Hz) passes through three plane polarizers. The first two polarizers are in the same direction, while the third is rotated 90° with respect to the second polarizer. What is the frequency of the light that comes out of the third polarizer? 3.0 × 1014 Hz 6.0 × 1014 Hz 9.0 × 1014 Hz Light will not pass through the third polarizer" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
D "Plane-polarized light is light in which the electric fields of all the waves are oriented in the same direction. Light passing through the first two polarizers will only contain rays with their electric field vectors in the same direction. When it reaches the third polarizer, however, the light will not be able to pass through because all the light rays will be oriented in the direction dictated by the first and second polarizers." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
"A submarine is inspecting the surface of the water with a laser that points from the submarine to the surface of the water and through the air. At what angle will the laser not penetrate the surface of the water but rather reflect entirely back into the water? (Assume nwater = 1.33 and nair = 1.) 19° 29° 39° 49°" Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
D "This question is testing our understanding of total internal reflection. As the laser beam travels from water to air—that is, from a higher to a lower index of refraction—the angle of refraction increases. At the critical angle (θc), the angle of refraction becomes 90°; at this point, the refracted ray is parallel to the surface of the water. When the incident angle is greater than the critical angle, all the light is reflected back into the water. The question is asking for the critical angle: 0c= sin-1 n2/n1= sin-1 1/1.33= sin-1.75 The inverse sine of 0.75 must be slightly higher than 45 degrees 48.59° is the exact answer." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
rainbow mneonimc
ROY G BV for longer wavelength to shorter wavelength violet: 400 nm, red: 700 nm
law of reflection
angle of incidence = angle of reflection
speed of light
c, 3 e8, " In reference to electromagnetic waves, the familiar equation ν = fλ becomes c = fλ Equation 8.1 where c is the speed of light in a vacuum and, to a first approximation, also in air, f is the frequency, and λ is the wavelength." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
spherical mirrors
concave and convex center of curvature: C, radius of curvature r
magnification
dimensionless value that is ratio of image distance to object distance m= -i/o also gives ratio of size of image to size of object negative value implies inverted image, positive indicates an upright image ". If |m| < 1, the image is smaller than the object (reduced); if |m| > 1, the image is larger than the object (enlarged); and if |m| = 1, the image is the same size as the object."
power
diopters, f= focal length (meters) given by eq: p= 1/f "P has the same sign as f and is, therefore, positive for a converging lens and negative for a diverging lens. People who are nearsighted (can see near objects clearly) need diverging lenses, while people who are farsighted (can see distant objects clearly) need converging lenses. Bifocal lenses are corrective lenses that have two distinct regions—one that causes convergence of light to correct for farsightedness (hyperopia) and a second that causes divergence of light to correct for nearsightedness (myopia) in the same lens." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
focal length
distance between folcal point and mirror focal length= r/2, r= radius of curvature (distance between C and mirror distance between object and mirror is o, distance between image and mirror is i
dark fringes (minima) eq
dsin0= (n+1/2)λ "where d is the distance between the two slits, θ is the angle between the line drawn from the midpoint between the two slits to the dark fringe and the normal, n is an integer indicating the number of the fringe, and λ is the wavelength of the incident wave. Note that bright fringes are halfway between dark fringes."
plane mirrors
flat mirror; reflecting surface that has no curvature does not cause convergence or divergence of reflected light rays PLANE MIRRORS ALWAYS MAKE VIRTUAL IMAGES -image appears to be same distance behind mirror as object infront of it " plane mirrors create the appearance of light rays originating behind the mirrored surface. Because the reflected light remains in front of the mirror but the image appears behind the mirror, the image is virtual. Plane mirrors include most of the common mirrors found in our homes. To assist in our discussion of spherical mirrors, plane mirrors can be conceptualized as spherical mirrors with an infinite radius of curvature." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
ray diagrams
helps determine type of image that will be produced (real vs. virtual, inverted vs. upright, magnified vs. reduced
object placed beyond focal point
image is real, inverted, magnifie
electromagnetic spectrum
lowest energy to highest energy (long wavelenth, low frequency, low energy): radio, micro, infared, visible, ultraiolet and x-rays, gamma rays wavelengths of visible light: 400 nm to 700 nm
snells law
n=c/v, n₁sinθ₁=n₂sinθ₂, where n is index of refraction "where c is the speed of light in a vacuum, ν is the speed of light in the medium, and n is a dimensionless quantity called the index of refraction of the medium. The index of refraction of a vacuum is 1, by definition; for all other materials, the index of refraction will be greater than 1. For air, n is essentially equal to 1 because the speed of light in air is extremely close to c." Excerpt From: Kaplan Test Prep. "MCAT Physics and Math Review 2021-2022." Apple Books.
object placed at focal point
parallel rays, no image produced
object between focal point and mirror
virtual, upright, magnified
