Question 1

Light having a speed in vacuum of 3.0 × 10⁸ m/s enters a liquid of refractive index 2.0.In this liquid,its speed will be

Accepted Answer

The speed of light in a medium is given by v = c/n, where c is the speed of light in vacuum and n is the refractive index of the medium. So, in this case, the speed of light in the liquid will be v = (3.0 × 10^8 m/s)/2 = 1.5 × 10^8 m/s. Therefore, the correct answer is C) 1.5 × 10^8 m/s.

Question 2

A beam of light,traveling in air,strikes a plate of transparent material at an angle of incidence of 56.0°.It is observed that the reflected and refracted beams form an angle of 90.0°.What is the index of refraction of this material?

Accepted Answer

The answer of A beam of light,traveling in air,strikes a...

Question 3

Starting from very far away,an object is moved closer and closer to a converging lens,eventually reaching the lens.What happens to its image formed by that lens? (There could be more than one correct choice. )

Accepted Answer

As the object gets closer to the converging lens, the image formed by the lens moves away from the lens and becomes larger. At a certain point, the image changes from real to virtual, and the distance between the lens and the image decreases. This means that the image is now formed behind the lens, rather than in front of it. As the object continues to move closer to the lens, the image continues to move closer to the lens and becomes smaller. Eventually, the image disappears when the object is at the focal point of the lens. After that, the image becomes virtual again, and moves away from the lens as the object gets closer to it. Therefore, D is the correct answer, as the image eventually changes from real to virtual.

Question 4

Which of following statements about the image formed by a single converging lens are true? (There could be more than one correct choice. )

Accepted Answer

A single converging lens can form both real and virtual images, and these images can be either upright or inverted depending on the object's position relative to the focal point. Therefore, none of the statements A, B, C, or D are always true.

Question 5

The index of refraction of a certain glass is measured to be 1.5.What is the speed of light in that glass? (c = 3.0 × 10⁸ m/s)

Accepted Answer

The speed of light in a medium is given by v = c/n, where c is the speed of light in vacuum and n is the index of refraction of the medium. So, v = (3.0 × 10^8 m/s)/(1.5) = 2.0 × 10^8 m/s. Therefore, the best choice is B.

Question 6

If a object is placed between a convex lens and its focal point,the image formed is

Accepted Answer

When an object is placed between a convex lens and its focal point, the image formed is virtual and upright because the light rays diverge after passing through the lens, making it impossible for them to meet on the same side as the object. The lens then forms a virtual image on the same side as the object, which appears upright compared to the object.

Question 7

A thin beam of light enters a thick plastic sheet from air at an angle of 32.0° with the normal and continues in the sheet at an angle of 23.0° with the normal.What is the index of refraction of the plastic?

Accepted Answer

The index of refraction of the plastic can be found using Snell's Law, which is $n_1 \sin(\theta_1) = n_2 \sin(\theta_2)$, where $n_1$ and $n_2$ are the indices of refraction of the first and second medium respectively, and $\theta_1$ and $\theta_2$ are the angles of incidence and refraction respectively. Given that the light enters from air (with $n_1 = 1$) at an angle of $32.0^\circ$ and continues in the plastic at an angle of $23.0^\circ$, we can solve for $n_2$, the index of refraction of the plastic, as follows:$$1 \times \sin(32.0^\circ) = n_2 \times \sin(23.0^\circ)$$Solving for $n_2$ gives an index of refraction of approximately 1.36.

Question 8

Which statement about a single thin lens is correct?

Accepted Answer

Diverging lenses always produce images that are virtual and upright, regardless of the object's position relative to the lens.

Question 9

A beam of light traveling in air strikes a slab of transparent material.The incident beam makes an angle of 40° with the normal,and the refracted beam make an angle of 26° with the normal.What is the speed of light in the transparent material? (c = 3.0 × 10⁸ m/s)

Accepted Answer

The answer of A beam of light traveling in air...

Question 10

If the magnification of a mirror or lens is negative,it means that

Accepted Answer

A negative magnification indicates that the image formed by a mirror or lens is inverted relative to the object. It does not necessarily imply anything about the size of the image or its distance relative to the object or mirror/lens.

Question 11

An oil layer that is 5.0 cm thick is spread smoothly and evenly over the surface of water on a windless day.A light ray from the air above enters the oil at 45° with the normal and then goes into the water.What is the angle of refraction of this ray in the water? The index of refraction for the oil is 1.15,and for water it is 1.33.

Accepted Answer

First, use Snell's Law for the air-oil interface: $n_1 \sin(\theta_1) = n_2 \sin(\theta_2)$, where $n_1 = 1$ (for air), $\theta_1 = 45^\circ$, and $n_2 = 1.15$ (for oil). Solving for $\theta_2$ gives the angle of refraction in the oil. Then, use Snell's Law again for the oil-water interface with $n_2 = 1.15$ (for oil), $n_3 = 1.33$ (for water), and the previously found $\theta_2$ to find $\theta_3$, the angle of refraction in the water. The correct calculation leads to an angle close to 32°.

Question 12

If a single lens forms a virtual image of an object,then

Accepted Answer

A virtual image is formed when the light rays appear to be coming from a point behind the lens, rather than actually converging at that point. This can happen with both converging and diverging lenses, depending on the position of the object relative to the lens. Therefore, it is not possible to determine the type of lens based solely on the fact that a virtual image has been formed.

Question 13

Starting from very far away,an object is moved closer and closer to a diverging lens,eventually reaching the lens.What happens to its image formed by that lens? (There could be more than one correct choice. )

Accepted Answer

The answer of Starting from very far away,an object is...

Question 14

A convex lens has focal length f.If an object is placed at a distance beyond 2f from the lens on the principal axis,the image is located at a distance from the lens

Accepted Answer

When an object is placed beyond 2f from a convex lens, the image formed is real, inverted, and located between f and 2f from the lens on the opposite side of the object.

Question 15

An object is placed on the left side of a thin lens,and the image of this object is formed on the left side of the lens.Which of the following statements must be true? (There could be more than one correct choice. )

Accepted Answer

The answer of An object is placed on the left...

Question 16

An object is placed in front of a thin lens.Which statements are correct in describing the image formed by the lens? (There could be more than one correct choice. )

Accepted Answer

B) Real images formed by lenses are inverted due to the way light rays converge after passing through the lens. D) Concave lenses diverge light rays, making it impossible for the rays to converge on the same side as the object, thus always forming a virtual image.

Question 17

The image formed by a single concave lens

Accepted Answer

A single concave lens always forms virtual images because the light rays diverge after passing through the lens, making it impossible for them to converge and form a real image on the opposite side of the lens.

Question 18

Which of following statements about the image formed by a single diverging lens are true? (There could be more than one correct choice. )

Accepted Answer

A diverging lens always forms a virtual and upright image.

Question 19

Is it possible to see a virtual image?

Accepted Answer

Virtual images can appear to the eye just like real images do, and the rays that appear to come from a virtual image can be focused by the eye just like those from an object. However, virtual images do not actually exist and cannot be projected onto a screen.

Question 20

The speed of light in a certain material is measured to be 2.2 × 10⁸ m/s.What is the index of refraction of this material? (c = 3.0 × 10⁸ m/s)

Accepted Answer

The index of refraction is defined as the ratio of the speed of light in a vacuum to the speed of light in the material. 
n = c/v, where c is the speed of light in vacuum and v is the speed of light in the material. 
Substituting the given values, 
n = c/v = (3.0 × 10^8 m/s)/(2.2 × 10^8 m/s) = 1.36 
Therefore, the closest choice is C, 1.4.

Quiz 26: Geometrical Optics

Light having a speed in vacuum of 3.0 × 108 m/s enters a liquid of refractive index 2.0.In this liquid,its speed will be