All AP Physics 2 Resources
Example Questions
Example Question #1 : Types Of Image
For a nearsighted person, the image of a distant object is formed __________.
in front of the retina, and corrected using a converging lens
behind the retina, and corrected using a diverging lens
in front of the retina, and corrected using a diverging lens
behind the retina, and corrected using a converging lens
in front of the retina, and corrected using a diverging lens
In nearsightedness, the person cannot see far objects due to increased refraction. This causes the image to be formed in front of the retina. This condition is corrected using a diverging lens to compensate for the "over refraction" by the deformed cornea.
Example Question #1 : Mirrors And Lenses
In a microscope has a tube length and objective lens with a focal length of . The viewer's eye is from the objective lens, and they desire a magnification of . What must the focal length of the eyepiece lens be to achieve this magnification?
The total magnification of a compound microscope is the product of the objective lens magnification and the eyepiece magnification.
Objective magnification and eyepiece magnification are given by the following equations:
We are given the tube length and focal length of the objective lens, allowing us to solve for its magnification.
We also know the distance of the viewer's eye. Use this value in the eyepiece magnification equation.
Finally, combine the eyepiece magnification and objective lens magnification into the original equation for total magnification.
Use the given value for total magnification to solve for the focal length of the eyepiece lens.
Example Question #11 : Mirrors And Lenses
Jimmy is farsighted and uses a convex lens to correct his vision. Wendy is nearsighted and uses a concave lens to correct her vision. They both wear glasses. During a camping trip, they notice they do not have any matches, and decide to use their glasses to start the fire. Whose glasses could be used to start the fire?
Wendy
Jimmy
Neither glasses would work
Both glasses would work equally well
Jimmy
This question deals with an application of optics. In this case we have a farsighted person and a near sighted person. The farsighted person would use a convex lens, which is a converging lens. This would allow all of the rays of light to converge on a single point, allowing them to heat the object up and start a fire. Wendy’s glasses are diverging lenses, which would cause the rays to separate.
Example Question #121 : Ap Physics 2
A monochromatic light ray passes from air (n = 1.00) into glass (n = 1.50) at an angle of 20o with respect to the normal. What is the approximate angle of refraction?
24o
27o
17o
31o
13o
13o
To compare angles of incidence and refraction, use Snell's law.
Notice that as the light enters a more dense medium, it bends towards the normal.
Example Question #1 : Polarization
Unpolarized light passes through three polarizing filters. The angle between the first and second filters is 45o. The angle between the second and third filters is also 45o. What is the relationship between the intensity of light emerging from the third filter, , and the incident intensity, ?
No light passes through the third filter
Going through the first filter, the intensity of initially unpolarized light decreases by 1/2, so . For each filter after the first, the intensity decreases by an additional factor of , where is the angle between adjacent polarizers. So, after the second filter, we have can see that . Similarly, after the third filter, we have .
Example Question #122 : Ap Physics 2
A man stands ten meters away from a converging mirror with a focal length of two meters. What is true of the image he sees?
His image is virtual, upright, and magnified
His image is real, inverted, and magnified
His image is virtual, upright, and minimized
His image is real, upright, and magnified
His image is real, inverted, and minimized
His image is real, inverted, and minimized
The first thing to consider when answering this question is the fact that real images are always inverted and virtual images are always upright. Once you have determined one or the other, two answer choices can be eliminated.
The first equation that is necessary for this question is .
From this we can determine that is equal to . Since is a positive number we know the image is real, and thus inverted.
The second equation to consider is for magnification: .
If the absolute value of is greater than one, the image is magnified, and if the value is less than one, it is minimized.
We would expect the image to be minimized.
Example Question #1 : Thin Lens Equation
How far from a converging lens must an object be placed to produce an image that is NOT real and inverted? Given the answer as in terms of the focal length, .
When an object is placed a distance from a converging lens or mirror that is equal to the focal length, no image is produced. To test this out, stand in front of a single concave mirror and continue to back up until you no longer see an image. Once you've reached this point, you will be standing one focal length away from the mirror.
When the object is less than one focal length away from the converging lens/mirror, the image will be virtual and upright.
If you don't have these trends committed to memory, you can derive them from the equation .
When is a negative integer the image is virtual, and when it is a positive integer the image is real.
Example Question #1 : Thin Lens Equation
A certain farsighted person cannot focus on objects closer to his eyes than . What focal length eyeglass lenses are needed in order to focus on a newspaper held at from the person's eyes, if the glasses are worn from his eyes?
First we need the object and image distances away from the eyeglass lenses. Here, the newspaper is the object and the focal point is where the image needs to be located. Find the distance from the object to the lens, and the distance of the image to the lens, by subtracting out the distance from the lens to the eye.
Now apply the thin lens equation to determine focal length.
Recall that if the image is on the same side of the lens as the object, then image distance is negative.
Example Question #1 : Mirrors And Lenses
A person approaches a plane mirror at 5m/s. How fast do they approach the mirror image?
5m/s
2.5m/s
10m/s
7.5m/s
10m/s
The image distance for a plane mirror is always equal to the object distance because the magnification is 1.
If the object and image are the same distance from the mirror and magnification is 1, then as the object approaches the mirror at a certain speed, the image is approaching the plane mirror at the same speed, therefore you approach the image more quickly than you approach the mirror, since you travel 5m/s toward the mirror and the image travels 5m/s toward the mirror.
Example Question #4 : Gre Subject Test: Physics
A virtual image is formed from a convex mirror with a focal length of . How far from the mirror is the object that created this image?
Use the equation:
Focal length is negative for convex mirrors, and image distance is negative for virtual images. We are given these values in the question, allowing us to calculate the object distance.
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