Physics Chapter on Refraction and Image Speed

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Questions and Answers

What is the average speed of the image when the jogger moves between 39 m and 34 m from the mirror?

1/1400 m s–1

1/360 m s–1

1/700 m s–1

1/280 m s–1 (correct)

When the jogger moves closer to the mirror, how does the speed of the image appear to change?

The speed appears to increase substantially. (correct)

The speed fluctuates randomly.

The speed remains constant.

The speed decreases.

What phenomenon occurs when a light beam encounters a transparent medium?

Reflection

Absorption

Refraction (correct)

Diffraction

At what angle does refraction of light occur when entering a new medium?

Any angle between 0° and 90° Signup and view all the answers

If a jogger is initially at –39 m and moves at a constant speed of 5 m s–1, what will be the new position after 1 second?

–34 m Signup and view all the answers

For a jogger moving between –29 m, –19 m, and –9 m, what will the observed speed of the image be at each position?

1/150 m s–1, 1/60 m s–1, 1/10 m s–1 Signup and view all the answers

What effect can a rear-moving vehicle have on a stationary observer?

It appears to be moving closer at a constant speed. Signup and view all the answers

In the context of refraction, what happens to the direction of a light ray at the interface of two media?

It changes direction. Signup and view all the answers

What is the primary function of prisms that utilize total internal reflection?

To bend light by specific angles Signup and view all the answers

In optical fibres, what characteristic of the core and cladding is essential for total internal reflection?

The core has a higher refractive index than the cladding Signup and view all the answers

What happens to light signals in optical fibres as they get transmitted?

They undergo multiple reflections without loss Signup and view all the answers

Which condition must be met for total internal reflection to occur in a prism?

The critical angle must be less than 45° Signup and view all the answers

What is the importance of bending an optical fibre?

It allows light to travel along its length without loss Signup and view all the answers

Which of the following is NOT a use of optical fibres?

Conducting electricity Signup and view all the answers

What is the role of transducers in relation to optical fibres?

They convert electrical signals to light Signup and view all the answers

What visual effect does a prism designed to invert images create?

It inverts the image without changing its size Signup and view all the answers

What occurs during total internal reflection?

No transmission of light takes place. Signup and view all the answers

What is the critical angle in the context of refraction?

The angle of incidence that results in total internal reflection. Signup and view all the answers

According to Snell's law, what happens if the angle of incidence exceeds the critical angle?

Refraction cannot occur. Signup and view all the answers

Which of the following best describes the refractive index of a denser medium with respect to a rarer medium?

It can be calculated as 1/sin(ic). Signup and view all the answers

When the angle of incidence is increased beyond the critical angle, what is the state of the reflected ray compared to the incident ray?

The reflected ray is always less intense than the incident ray. Signup and view all the answers

What is the relationship between the angle of refraction and the critical angle?

The angle of refraction is never larger than the critical angle. Signup and view all the answers

In which case does light graze the surface at the interface?

When the angle of incidence is equal to the critical angle. Signup and view all the answers

Which of the following statements about light reflection is true?

When light reflects at total internal reflection, there is no transmission. Signup and view all the answers

What happens to the object distance $OB$ when the object is at infinity?

It becomes infinitely large Signup and view all the answers

What does the equation $\frac{n_1}{OB} + \frac{n_2}{BI_1} = \frac{n_2 - n_1}{BC_1}$ represent?

The behavior of light passing through boundaries between materials Signup and view all the answers

Which statement accurately describes the focal length $f$ of a lens?

It indicates the distance at which light rays converge when the object is at infinity Signup and view all the answers

According to the derived equation, if $n_1 = 1.5$ and $n_2 - n_1 = 0.5$, which of the following can be inferred about the light behavior?

Light will refract and possibly focus beyond the lens Signup and view all the answers

In the context of a thin lens, what can be stated about $BI_1$ and $DI_1$?

They are always equal regardless of object position Signup and view all the answers

What does the term 'focus F' refer to in lens optics?

The point where the image of an object placed at infinity is formed Signup and view all the answers

What does the equation $\frac{n_1}{DI} + \frac{n_1}{DI_1} = (n_2-n_1)(\frac{1}{BC_1} + \frac{1}{DC_2})$ suggest about the relationship between distances and indices?

An inverse relationship exists between indices and distances Signup and view all the answers

Which of the following describes the conditions necessary to derive equations for lens optics?

Interaction between at least two different media Signup and view all the answers

What does the lens maker's formula help to design?

Lenses of desired focal length Signup and view all the answers

In the context of the lens maker's formula, what does a positive value for R1 indicate?

The lens is convex Signup and view all the answers

For a concave lens, what is true regarding the value of R1?

R1 is negative and R2 is positive Signup and view all the answers

Which equation represents the thin lens formula?

1/f = 1/v + 1/u Signup and view all the answers

What does a negative value for DI1 indicate in the context of lens optics?

The image distance is measured against the light direction Signup and view all the answers

In a double convex lens, what is the significance of the two foci?

They are equidistant from the optical centre Signup and view all the answers

What does equation (9.22) represent in lens optics?

The relationship of refractive indices and distances Signup and view all the answers

What type of images can the thin lens formula apply to?

Both real and virtual images from any type of lens Signup and view all the answers

Study Notes

Jogger and Image Speed

A jogger moving at a constant speed of 5 m/s towards a mirror appears to have an image that moves at an increasing speed as the jogger gets closer to the mirror.
The image speed is calculated using the formula for image position (v) in relation to the jogger's position (u) and the mirror's focal length.
For example, when the jogger is 39 m from the mirror, the image's speed is 1/280 m/s. This speed increases to 1/150 m/s when the jogger is 29 m away.

Refraction and Total Internal Reflection

Refraction is the bending of light as it passes from one medium to another, such as from air to water.
Total internal reflection occurs when light traveling from a denser medium (e.g., water) to a rarer medium (e.g., air) hits the interface at an angle greater than the critical angle.
The critical angle is the angle of incidence that produces an angle of refraction of 90 degrees.
The critical angle can be calculated using the formula sin(ic) = n21, where n21 is the refractive index of the rarer medium relative to the denser medium.

Total Internal Reflection Applications

Prisms designed to bend light by 90° or 180° utilize total internal reflection.
Optical fibers use total internal reflection to transmit light signals over long distances. Optical fibers consist of a core with higher refractive index and a cladding with a lower refractive index.

Thin Lens Formula

The lens maker's formula relates the focal length (f) of a lens to the radii of curvature (R1, R2) of its surfaces and the refractive index (n1, n2) of the lens material and the surrounding medium:
```
1/f = (n2 - n1) * (1/R1 - 1/R2) 
```
For a thin lens, the thin lens formula relates the object distance (u), image distance (v), and focal length (f):
```
1/v - 1/u = 1/f
```
The focal length is positive for a converging lens (convex) and negative for a diverging lens (concave).

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Description

Explore the concepts of image speed as a jogger approaches a mirror and the principles of refraction and total internal reflection. This quiz tests your understanding of these crucial physics topics, including calculations for image speed and determining critical angles. Challenge yourself with problems based on real-life scenarios involving light and motion.