Question 1

Reducing the lens aperture size is a scheme one can use to reduce the occurrence of which of the following effects?

Accepted Answer

Reducing the lens aperture size is a way to reduce the occurrence of spherical aberration, which causes the image to be blurry and out of focus. It does not affect mirages, chromatic aberration, or light scattering.

Question 2

An image is formed using a convex lens,the image being 15 cm past the lens.A second lens is placed 25 cm past the first lens and another image is formed,this time 10 cm past the second lens.Which of the following statements is always true?

Accepted Answer

Convex lenses are converging lenses, which means they have positive focal lengths. The formation of real images past each lens indicates that both lenses are converging, thus having positive focal lengths.

Question 3

In an ideal case rays coming from an object toward a lens or mirror should be reasonably close to the optic axis.To the extent that this condition is not completely met,which one of the following effects occurs?

Accepted Answer

When rays coming from an object are not reasonably close to the optic axis, spherical aberration occurs. This happens when the light rays that pass through the edges of the lens or mirror are focused differently than those passing through the center, resulting in blurry images. Mirages are caused by the refraction of light in a different medium, chromatic aberration is caused by the dispersion of light, and light scattering occurs when light is dispersed in different directions due to irregularities in the medium.

Question 4

Which of the following effects is the result of the fact that the index of refraction of glass will vary with wavelength?

Accepted Answer

Chromatic aberration is the effect caused by the variation of refractive index with wavelength, which leads to the formation of color fringes or blurred images. Spherical aberration is caused by imperfectly shaped lenses, mirages are caused by light bending in hot air layers, and light scattering is caused by multiple reflections or refractions in different directions.

Question 5

An object is placed 27.0 cm to the left of a lens of focal length 17.0 cm.39.0 cm to the right of this lens is a plane mirror.Where does the final image form?

Accepted Answer

First, we need to find the position of the image formed by the lens alone. We can use the lens formula:
1/f = 1/do + 1/di
where f is the focal length, do is the object distance, and di is the image distance.
Substituting the given values, we get:
1/17 = 1/27 + 1/di
Solving for di, we get:
di = 45.9 cm
So, the image formed by the lens is 45.9 cm to the left of the lens.
Now, this image acts as the virtual object for the plane mirror. The distance between the image and the mirror is 39 cm, so the distance between the virtual object and the mirror is also 39 cm.
Using the mirror formula:
1/do' + 1/di' = 1/f'
where f' is the focal length of the mirror, which is infinity for a plane mirror, and do' and di' are the object and image distances measured from the mirror.
Since the object is at infinity, we can simplify the formula to:
1/di' = 1/f'
Solving for di', we get:
di' = -39 cm
The negative sign indicates that the image is formed behind the mirror, which is expected for a plane mirror.
So, the final image is 39 cm behind the mirror, which is equivalent to 6.9 cm to the left of the mirror. Therefore, the answer is B.

Question 6

When light goes through two or more separated lenses,

Accepted Answer

The answer of When light goes through two or more...

Question 7

A convex lens has a focal length of magnitude F.At which of the following distances from this lens would a real object give an inverted virtual image?

Accepted Answer

A convex lens cannot produce an inverted virtual image; it produces real, inverted images or virtual, upright images depending on the object's position relative to the focal length.

Question 8

A contact lens is made of plastic with an index of refraction 1.50.The lens has an outer radius of curvature of + 1.65 cm and an inner radius of curvature of + 5.85 cm.What is its focal length?

Accepted Answer

The answer of A contact lens is made of plastic...

Question 9

A concave mirror with focal length 16.0 cm is placed 45.0 cm to the left of the object.A convex lens of focal length 15.0 cm is placed 6.0 cm to the right of the object.Where is the image formed by both the mirror and the lens?

Accepted Answer

The image formed by the concave mirror is virtual and located 9.5 cm to the right of the object. This virtual image acts as the object for the convex lens, which then forms a real image 35.1 cm to the right of the lens.

Question 10

An eyeglass lens is cut with one surface having a radius R₁ and the other surface having a radius R₂,with R₁ < R₂.Both positive radii are measured from the same side with R₁ being the side closer to the eye.Is this convex-concave lens a converging lens or a diverging lens?

Accepted Answer

A convex-concave lens with R₁ < R₂ is a diverging lens because the surface with the smaller radius (R₁) is more curved and closer to the eye, causing light rays to diverge.

Question 11

A fused combination of a diverging and converging lens pair each made from a different index of refraction glass,is used to reduce the occurrence of which of the following effects?

Accepted Answer

A fused combination of a diverging and converging lens pair made from different index of refraction glass is known as an achromatic lens. It is specifically designed to reduce chromatic aberration, which is the effect of different colors of light being refracted differently and causing a blurred or distorted image.

Question 12

A real object is place to the left of a converging lens and an image forms.Then,to the right of the converging lens a diverging lens is placed.A real,inverted final image forms to the right of the diverging lens.Which of the following could give this result?

Accepted Answer

When a real, inverted image is formed to the left of a diverging lens, it acts as a virtual object for the diverging lens. The diverging lens then produces a virtual, upright image to the right of it. Therefore, the real, inverted final image can only be produced if a real, inverted image was formed by the converging lens to the left of where the diverging lens is placed. Thus, the correct choice is D.

Question 13

Use of a parabolic mirror,instead of one made of a circular arc surface,can be used to reduce the occurrence of which of the following effects?

Accepted Answer

A parabolic mirror is designed to eliminate spherical aberration, which occurs when a spherical mirror fails to focus all parallel rays to a single point. Mirages, chromatic aberration, and light scattering are not affected by the shape of the mirror surface, and therefore using a parabolic mirror instead of a circular arc surface mirror would not reduce these effects.

Question 14

A thin lens has a focal length of 10.00 cm for red light.If the index of refraction for the lens material tends to decrease with increasing wavelength,what is the focal length of the lens for blue light?

Accepted Answer

Since the index of refraction decreases with increasing wavelength, blue light will have a higher refractive index than red light. This means that blue light will be refracted more than red light, causing the focal length of the lens to be shorter for blue light. Therefore, the focal length of the lens for blue light will be less than 10.00 cm.

Question 15

A lens has a focal length of 56.2 cm in air.If this lens were immersed in water,what focal length would result? The index of refraction of the lens is 1.96 and that of water is 1.333.The focal length of a thin lens with index n₁ submerged in a liquid with index n₂ is given by the modified lens-maker's formula: )

Accepted Answer

The answer of A lens has a focal length of...

Question 16

A concave mirror has radius R.When an object is located a distance 2R from the lens,which describes the image formed?

Accepted Answer

The image formed by a concave mirror when the object is located at a distance of 2R from the mirror is real, inverted, and diminished. This is because the object is located beyond the center of curvature of the mirror, which results in a real image being formed. The image is inverted because the rays of light from the object cross at a point behind the mirror, and the image is diminished because the object is farther from the mirror than the image.

Question 17

A lens of 15.0-cm focal length is placed 21.0 cm to the right of the object and a mirror of focal length -22.0 cm is placed 59.0 cm to the right of the lens.Where is the image formed by the mirror?

Accepted Answer

The answer of A lens of 15.0-cm focal length is...

Question 18

A real object is place a distance d from a converging lens.The object is then moved to a distance 2d from the converging lens.Which of the following statements is false?

Accepted Answer

Option D is false because if the image in the first case is real, it must be inverted according to the laws of refraction, and when the object is moved to a distance 2d from the lens, the image will also be inverted. So, the image in the second case will not be upright. Options A, B, and C are all true statements. The image in the first case can be larger or smaller, depending on the position of the object with respect to the lens. Similarly, the image in the second case can also be larger or smaller. If both images are real, the image in the second case will be smaller as the distance between the object and the lens is increased.

Quiz 23: Mirrors and Lenses