Define angle of incidence .

The angle of incidence is the angle between the incident ray and the normal .

Define angle of reflection .

The angle of reflection is the angle between the reflected ray and the normal .

What is the normal , in a ray diagram?

An imaginary line drawn at right angles (90°) to the boundary, used to measure the angles of incidence and reflection.

An incident ray has an arrow pointing ______ the boundary, while a reflected ray has an arrow pointing ______ the boundary.

An incident ray has an arrow pointing towards the boundary, while a reflected ray has an arrow pointing away from the boundary.

True or False? In a ray diagram, the angle of incidence and angle of reflection are measured from the boundary itself.

False. Both angles are measured from the normal , the line drawn at 90° to the boundary, not from the boundary itself.

Name the control variables in the investigating reflection experiment.

The distance of the ray box from the mirror and the width of the light beam (the frequency/wavelength of the light must also be kept the same).

How can a systematic error from inaccurately drawn 90° lines be reduced in this experiment?

Use a set square to draw the perpendicular (90°) line accurately.

In the method, a point is marked on the reflected beam about ______ cm away from the mirror.

In the method, a point is marked on the reflected beam about 10 cm away from the mirror.

True or False? The mirror is placed along the 90° line that bisects the original straight line drawn on the paper.

False. The mirror is placed along the original 10 cm line ; the 90° line is the normal, used only to measure the angles of incidence and reflection.

True or False? When light refracts by passing from a less dense medium into a denser medium, the ray bends away from the normal.

False. When light refracts by passing from a less dense medium to a more dense medium, it bends towards the normal.

True or False? The frequency of light changes during refraction.

False. The frequency of light does not change during refraction.

True or False? When light passes along the normal, perpendicular to the surface of a medium, the ray does not change direction.

True. When light passes along the normal, perpendicular to the surface of a medium, the ray does not change direction.

True or False? When light refracts by passing from a denser medium into a less dense medium, the ray bends toward the normal.

False. When light refracts by passing from a denser medium into a less dense medium, the ray bends away from the normal.

What properties of light change during refraction?

During refraction, the speed and wavelength of light change, but not the frequency.

In a ray diagram of refraction through a glass block, how many boundary surfaces does the ray pass through?

In a ray diagram for refraction through a glass block, the ray passes through 2 boundary surfaces: air-to-glass glass-to-air

True or False? When light refracts through a glass block, the incident ray at the boundary of glass-to-air is the ray inside the glass.

True. When light refracts through a glass block, the first boundary is air-to-glass, and the second boundary is glass-to-air. The refracted ray at the air-to-glass boundary becomes the incident ray at the glass-to-air boundary.

Define refractive index .

A number, always greater than 1 , that indicates how much a material slows down light; a higher refractive index means the material is more optically dense .

Glass has a refractive index of about 1.5 and diamond about 2.4. Which is more optically dense ?

Diamond — a higher refractive index means a material is more optically dense.

When light enters a denser medium, it slows down and bends ______ the normal.

When light enters a denser medium, it slows down and bends towards the normal.

True or False? Refractive index has units.

False. Refractive index is a ratio , so it has no units .

Define total internal reflection .

The phenomenon where light travelling from a denser medium into a less dense medium is completely reflected at the boundary, with none refracted out.

State the two conditions needed for total internal reflection to occur.

(1) The angle of incidence is greater than the critical angle . (2) The incident material is denser than the second material.

Define critical angle .

The angle of incidence, in the denser medium, above which light undergoes total internal reflection instead of refracting.

Name two applications of total internal reflection.

Optical fibres (e.g. endoscopes, communications) and prisms (e.g. periscopes, binoculars, telescopes, cameras, safety reflectors).

In an optical fibre, light is ______ each time it hits the edge of the fibre, allowing information to travel long distances with minimal loss.

In an optical fibre, light is totally internally reflected each time it hits the edge of the fibre, allowing information to travel long distances with minimal loss.

True or False? Whether light undergoes total internal reflection depends on comparing the angle of incidence with the angle of reflection.

False. Total internal reflection depends on comparing the angle of incidence with the critical angle , not the angle of reflection — TIR occurs when the angle of incidence exceeds the critical angle.

Define principal axis .

The principal axis is a line which passes through the centre of a lens.

Define principal focus (focal point).

The point at which rays of light travelling parallel to the principal axis converge (converging lens), or the point from which diverging rays appear to proceed (diverging lens).

Define focal length .

The focal length is the distance between the centre of a lens and the principal focus.

What happens to parallel rays of light passing through a converging lens?

They are refracted so that they converge (meet) at the principal focus.

What happens to parallel rays of light passing through a diverging lens?

They are refracted so that they diverge (spread out), appearing to come from the principal focus.

How does the curvature of a lens affect its focal length?

The more curved the lens, the shorter its focal length.

A converging lens is also known as a ______ lens, while a diverging lens is also known as a ______ lens.

A converging lens is also known as a convex lens, while a diverging lens is also known as a concave lens.

True or False? A diverging lens brings parallel rays of light to a focus.

False. A diverging lens causes parallel rays to spread out (diverge) from a point; it is a converging lens that brings rays to a focus.

An image that is formed when light rays from an object converge and meet each other, and which can be projected onto a screen.

Define virtual image .

An image that is formed when light rays from an object do not meet but appear to meet behind the lens, and which cannot be projected onto a screen.

How can a real image and a virtual image be distinguished on a ray diagram?

Real images are formed where two solid lines cross; virtual images are formed where two dashed lines (or one dashed and one solid line) cross.

What type of image is formed by a converging lens when the object is placed between f and 2 f ?

A real , enlarged , inverted image.

What type of image is formed by a converging lens when the object is placed further than 2 f away?

A real , diminished (smaller), inverted image.

What type of image is formed by a converging lens when the object is placed exactly at 2 f ?

A real image, the same size as the object, and inverted .

True or False? A converging lens can produce a virtual image if the object is placed closer to the lens than the focal length.

True. When the object distance is less than the focal length, the lens produces a magnified, upright virtual image instead of a real image.

Real images are always ______ , whereas virtual images are always ______ .

Real images are always inverted , whereas virtual images are always upright .

What two factors does the magnification produced by a lens depend on?

The distance of the object from the lens, and the power of the lens.

Why does magnification have no units?

Because it is a ratio of two lengths measured in the same units, so the units cancel out.

What does the value of a lens's magnification tell you about the image compared to the object?

If magnification is greater than 1 , the image is magnified . If it is equal to 1 , the image is the same size . If it is less than 1 , the image is diminished .

The units used for object and image height are unimportant, provided both are measured in the ______ units.

The units used for object and image height are unimportant, provided both are measured in the same units.

True or False? Object and image heights must both be measured in centimetres to calculate magnification.

False. The heights just need to be measured in the same units as each other (for example, both in cm or both in mm) — the specific unit does not matter.

Define the use of a lens as a magnifying glass .

A converging lens used to produce a magnified, virtual, upright image, by placing the object closer to the lens than the focal length.

What three characteristics describe the image formed by a magnifying glass?

Virtual , enlarged (magnified), and upright .

O LevelPhysicsCambridge (CIE)Flashcards3. Waves3.2 Light

3.2 Light (Cambridge (CIE) O Level Physics): Flashcards

Exam code: 5054

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FrontReflection of Light
Define angle of incidence.

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Cards in this collection (74)

Define angle of incidence.
The angle of incidence is the angle between the incident ray and the normal.
Define angle of reflection.
The angle of reflection is the angle between the reflected ray and the normal.
What is the normal, in a ray diagram?
An imaginary line drawn at right angles (90°) to the boundary, used to measure the angles of incidence and reflection.
State the law of reflection.
The angle of incidence is equal to the angle of reflection:
$i = r$
An incident ray has an arrow pointing ______ the boundary, while a reflected ray has an arrow pointing ______ the boundary.
An incident ray has an arrow pointing towards the boundary, while a reflected ray has an arrow pointing away from the boundary.
True or False?
In a ray diagram, the angle of incidence and angle of reflection are measured from the boundary itself.
False.
Both angles are measured from the normal, the line drawn at 90° to the boundary, not from the boundary itself.
What is the independent variable in the investigating reflection experiment?
The angle of incidence, i.
What is the dependent variable in the investigating reflection experiment?
The angle of reflection, r.
Name the control variables in the investigating reflection experiment.
The distance of the ray box from the mirror and the width of the light beam (the frequency/wavelength of the light must also be kept the same).
How can a systematic error from inaccurately drawn 90° lines be reduced in this experiment?
Use a set square to draw the perpendicular (90°) line accurately.
In the method, a point is marked on the reflected beam about ______ cm away from the mirror.
In the method, a point is marked on the reflected beam about 10 cm away from the mirror.
True or False?
The mirror is placed along the 90° line that bisects the original straight line drawn on the paper.
False.
The mirror is placed along the original 10 cm line; the 90° line is the normal, used only to measure the angles of incidence and reflection.
What is the symbol for the angle of incidence of a light ray on a boundary?
The symbol for the angle of incidence of a light ray on a boundary is $i$ .
What is the symbol for the angle of refraction of a light ray on a boundary?
The symbol for the angle of refraction of a light ray on a boundary is $r$ .
True or False?
When light refracts by passing from a less dense medium into a denser medium, the ray bends away from the normal.
False.
When light refracts by passing from a less dense medium to a more dense medium, it bends towards the normal.
True or False?
The frequency of light changes during refraction.
False.
The frequency of light does not change during refraction.
True or False?
When light passes along the normal, perpendicular to the surface of a medium, the ray does not change direction.
True.
When light passes along the normal, perpendicular to the surface of a medium, the ray does not change direction.
True or False?
When light refracts by passing from a denser medium into a less dense medium, the ray bends toward the normal.
False.
When light refracts by passing from a denser medium into a less dense medium, the ray bends away from the normal.
What properties of light change during refraction?
During refraction, the speed and wavelength of light change, but not the frequency.
In a ray diagram of refraction through a glass block, how many boundary surfaces does the ray pass through?
In a ray diagram for refraction through a glass block, the ray passes through 2 boundary surfaces:
- air-to-glass
- glass-to-air
True or False?
When light refracts through a glass block, the incident ray at the boundary of glass-to-air is the ray inside the glass.
True.
When light refracts through a glass block, the first boundary is air-to-glass, and the second boundary is glass-to-air. The refracted ray at the air-to-glass boundary becomes the incident ray at the glass-to-air boundary.
Define refractive index.
A number, always greater than 1, that indicates how much a material slows down light; a higher refractive index means the material is more optically dense.
State Snell's Law.
$n = \frac{\sin i}{\sin r}$
where n = refractive index, i = angle of incidence (°), r = angle of refraction (°)
Glass has a refractive index of about 1.5 and diamond about 2.4. Which is more optically dense?
Diamond — a higher refractive index means a material is more optically dense.
When light enters a denser medium, it slows down and bends ______ the normal.
When light enters a denser medium, it slows down and bends towards the normal.
A ray of light enters a glass block of refractive index 1.53, making an angle of incidence of 15°. Calculate the angle of refraction.
$\sin r = \frac{\sin i}{n} = \frac{\sin 15 °}{1.53} = 0.169$
$r = \sin^{- 1} (0.169) = 10 °$
True or False?
Refractive index has units.
False.
Refractive index is a ratio, so it has no units.
Define total internal reflection.
The phenomenon where light travelling from a denser medium into a less dense medium is completely reflected at the boundary, with none refracted out.
State the two conditions needed for total internal reflection to occur.
(1) The angle of incidence is greater than the critical angle.
(2) The incident material is denser than the second material.
Define critical angle.
The angle of incidence, in the denser medium, above which light undergoes total internal reflection instead of refracting.
State the equation relating critical angle, c, and refractive index, n.
$\sin c = \frac{1}{n}$
where c = critical angle (°), n = refractive index
Diamond has a higher refractive index than opal. Which stone has the smaller critical angle?
Diamond — the critical angle decreases as the refractive index increases:
$\sin c = \frac{1}{n}$
Name two applications of total internal reflection.
Optical fibres (e.g. endoscopes, communications) and prisms (e.g. periscopes, binoculars, telescopes, cameras, safety reflectors).
In an optical fibre, light is ______ each time it hits the edge of the fibre, allowing information to travel long distances with minimal loss.
In an optical fibre, light is totally internally reflected each time it hits the edge of the fibre, allowing information to travel long distances with minimal loss.
True or False?
Whether light undergoes total internal reflection depends on comparing the angle of incidence with the angle of reflection.
False.
Total internal reflection depends on comparing the angle of incidence with the critical angle, not the angle of reflection — TIR occurs when the angle of incidence exceeds the critical angle.
Define principal axis.
The principal axis is a line which passes through the centre of a lens.
Define principal focus (focal point).
The point at which rays of light travelling parallel to the principal axis converge (converging lens), or the point from which diverging rays appear to proceed (diverging lens).
Define focal length.
The focal length is the distance between the centre of a lens and the principal focus.
What happens to parallel rays of light passing through a converging lens?
They are refracted so that they converge (meet) at the principal focus.
What happens to parallel rays of light passing through a diverging lens?
They are refracted so that they diverge (spread out), appearing to come from the principal focus.
How does the curvature of a lens affect its focal length?
The more curved the lens, the shorter its focal length.
A converging lens is also known as a ______ lens, while a diverging lens is also known as a ______ lens.
A converging lens is also known as a convex lens, while a diverging lens is also known as a concave lens.
True or False?
A diverging lens brings parallel rays of light to a focus.
False.
A diverging lens causes parallel rays to spread out (diverge) from a point; it is a converging lens that brings rays to a focus.
Define real image.
An image that is formed when light rays from an object converge and meet each other, and which can be projected onto a screen.
Define virtual image.
An image that is formed when light rays from an object do not meet but appear to meet behind the lens, and which cannot be projected onto a screen.
How can a real image and a virtual image be distinguished on a ray diagram?
Real images are formed where two solid lines cross; virtual images are formed where two dashed lines (or one dashed and one solid line) cross.
What type of image is formed by a converging lens when the object is placed between f and 2f?
A real, enlarged, inverted image.
What type of image is formed by a converging lens when the object is placed further than 2f away?
A real, diminished (smaller), inverted image.
What type of image is formed by a converging lens when the object is placed exactly at 2f?
A real image, the same size as the object, and inverted.
True or False?
A converging lens can produce a virtual image if the object is placed closer to the lens than the focal length.
True.
When the object distance is less than the focal length, the lens produces a magnified, upright virtual image instead of a real image.
Real images are always ______, whereas virtual images are always ______.
Real images are always inverted, whereas virtual images are always upright.
Define linear magnification.
The ratio of the image height to the object height:
$m a g n i f i c a t i o n = \frac{image height}{object height}$
What two factors does the magnification produced by a lens depend on?
The distance of the object from the lens, and the power of the lens.
Why does magnification have no units?
Because it is a ratio of two lengths measured in the same units, so the units cancel out.
What does the value of a lens's magnification tell you about the image compared to the object?
If magnification is greater than 1, the image is magnified. If it is equal to 1, the image is the same size. If it is less than 1, the image is diminished.
The units used for object and image height are unimportant, provided both are measured in the ______ units.
The units used for object and image height are unimportant, provided both are measured in the same units.
True or False?
Object and image heights must both be measured in centimetres to calculate magnification.
False.
The heights just need to be measured in the same units as each other (for example, both in cm or both in mm) — the specific unit does not matter.
A magnifying glass forms an image 20 cm tall from an object 10 cm tall. Calculate the magnification.
$m a g n i f i c a t i o n = \frac{20}{10} = 2$
Define the use of a lens as a magnifying glass.
A converging lens used to produce a magnified, virtual, upright image, by placing the object closer to the lens than the focal length.
What three characteristics describe the image formed by a magnifying glass?
Virtual, enlarged (magnified), and upright.
Where must an object be placed relative to the focal length for a lens to act as a magnifying glass?
Closer to the lens than the focal length (f).
How should a magnifying glass be held relative to the object being viewed?
Held close to the object.
What type of lens corrects short-sightedness, and why?
A diverging (concave) lens; it causes light to focus further back, moving the focus point onto the retina instead of in front of it.
What type of lens corrects long-sightedness, and why?
A converging (convex) lens; it causes light to focus further forward, moving the focus point onto the retina instead of behind it.
People who are short-sighted have eyes that are '______', so light is focused ______ the retina.
People who are short-sighted have eyes that are 'too large', so light is focused in front of the retina.
True or False?
Long-sighted people cannot clearly see things that are close to them.
True.
Long-sighted people can see distant objects clearly, but cannot focus clearly on nearby objects because their eyes are 'too small' and light focuses beyond the retina.
Define dispersion of white light.
The splitting of white light into its component colours (a spectrum) as it passes through a prism, due to refraction.
What causes white light to split into a spectrum of colours when passing through a prism?
Refraction — each colour has a different wavelength and is refracted by a different amount.
Which colour of visible light is refracted the most by a prism, and which is refracted the least?
Violet is refracted the most; red is refracted the least.
What is white light composed of?
A mixture of all the colours of the visible spectrum.
Which colour of visible light has the longest wavelength, and which has the shortest?
Red has the longest wavelength (lowest frequency and energy); violet has the shortest wavelength (highest frequency and energy).
Visible light makes up only ______ of the whole electromagnetic spectrum.
Visible light makes up only 0.0035% of the whole electromagnetic spectrum.
True or False?
Visible light is the only part of the electromagnetic spectrum that can be detected by the human eye.
True.
All other regions of the electromagnetic spectrum (for example, infrared and ultraviolet) are undetectable by the unaided human eye.
Some animals, such as birds, bees and certain fish, can perceive light beyond the visible spectrum. Which two additional parts of the spectrum can they detect?
Infrared and ultraviolet.

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