Science 1-4

Ray diagram

helps demonstrate why brightness or intensity of light changes with distances.

Transparent

Light passes through it nearly or wholly undiffused.

Translucent

Allows some but not all light through.

Opaque

Allows no light through, they absorb or reflect the light.

Non-luminous

does not produce light.

Luminous

Gives off light.

Regular reflection

A flat surface so the rays go off the surface at the same angle they came on (incident ray).

Diffuse relfection

Not a flat surface, so the reflected rays are not the same angle.

Ray diagrams are useful but they do not show the complete picture. Why are they still considered useful?

They provide a simplified way to visualize the paths of light rays, helping to understand concepts like reflection and refraction.

How do ray diagrams help explain why the brightness, or intensity, of a light changes with distance?

They illustrate that as light travels further from the source, the same amount of light is spread over a larger area, decreasing intensity.

How do ray diagrams help explain shadows?

They demonstrate how light travels in straight lines and how objects can block this path, leading to areas of darkness or shadows where the object blocks the ray of light.

How can you change the direction of a ray of light?

Changing the surface that the ray of light reflects off of.

Which would make a better reflector, a piece of metal or a piece of wood? Explain why.

metal, because it is shiny and not as dark so it doesn't absorb the light as much as the wood, and metal is a flat surface so the ray would come back just as powerful and in the same degree as the light source.

Explain, with the help of ray diagrams, why the shadow created by your hand on a wall grows bigger when you move your hand toward the light source.

When you move your hand closer, it blocks more light rays making your shadow bigger, when you put your hand farther back it takes up less rays so the shadow is smaller.

Incident ray(s)

The incoming ray that will be reflected off.

Plane mirrors

Flat-surfaced mirrors.

Normal

The imaginary line that is perpendicular to the mirror.

Angle of incidence

The angle between the incident ray and the normal.

Angle of reflection

The angle between the reflected ray and the normal.

Law of reflection

The angle of incidence is equal to the angle of reflection.

How can light reflecting off of a smooth surface result in regular reflection?

Because since the reflector is a smooth surface, the ray can hit it properly, and the reflected ray will be the same degree as the incident ray, making the reflection just as strong as the actual thing that's being reflected.

What type of surface will result in a better reflection? What are some examples of materials that will allow you to see your image and provide you with the clearest reflection?

A surface that will result in a better reflection is a shiny and smooth flat surface, like a mirror.

With a diffuse reflection, do you think light rays obey the law of reflection?

No, because with diffuse reflection, the light rays change there degrees once they hit the reflector, so this law does not work for diffused reflections. In diffuse reflection, the light rays do not follow a uniform angle but scatter in different directions, which is violating the law of reflection.

Concave mirror

Has a surface that curves inward.

Focal point

The point where all light rays meet together.

What are concave mirrors good at doing?

Concave mirrors are good at collecting light and bringing it to one single point. they are ideal of reflecting telescopes where you want to gather as much light from a distant source and focus it for viewing. Other examples include headlight, flashlight, and cosmetic mirror.

What happens if you are looking into a concave mirror and you are far away from the focal point?

the object is inverted and smaller.

What happens if you are looking into a concave mirror and you are closer from the focal point?

The object gets larger, but still inverted.

What happens if you are looking into a concave mirror and you are past or on the focal point?

The object becomes upright and enlarged.

What kind of image will a concave mirror produce if the object is Infront of the focal point?

Virtual image, because the light rays don’t actually converge in frontIf an object is closer to the mirror, between the focal point and the mirror, then the light rays emitted from the object will not be able to cross in front of the mirror. The light rays, when extrapolated backward, will converge behind the mirror. This is why holding an object close to a concave mirror will produce a larger, erect, virtual image. The image is virtual because the light rays don’t actually converge in front of the mirror of the mirror.

convex mirror

surface curved outward. If you look in a convex mirror, it appears as if the image is originating from a smaller point behind the mirror. Because of these smaller images, convex mirrors on cars often have the warning “Objects in mirror are closer than they appear.”

Refraction

The bending of light as it passes from one medium/material into another.

What happens to light when it travels at an angle from one medium (substance) to another?

It refracts and changes its angle.

What causes refraction?

When light rays go from a denser material to a less denser material, or vice versa.

What happens to the bending behavior of light as it moves from a less dense medium to a more dense medium?

When the light moves to a more dense medium, it turns towards and closer to the normal.

How does the type of medium affect refraction?

If light goes into a less denser medium, the light refracts away from the normal, but if light goes into a more dense medium, it refracts towards the normal.

Lens

Piece of curved glass or other transparent material.

Concave lens

is thinner in the middle than at the edges. parallel light rays refract away from the center of the lens (diverge) Since the light rays diverge, they will never meet on the other side.

Convex lens

is thicker in the middle than at the edges. parallel light rays refract towards the center of the lens. (converge) The light rays cross at the focal point of the lens.

What makes a convex lens useful?

It acts as a light collector, and forms a real image when light rays meet at the focal point.

What would you change about the lens itself that would change its focal point?

You can change it the lens is a convex or concave, and how thick the lenses are, and the material as well.

Real image

When light rays meet at a point and the images can be projected onto a screen.

How does the shape of a lens impact its ability to refract light?

Depending on the curvature of the lens, depends where the light rays move off of when refracting.

Describe the shape of a concave lens. What happens to parallel rays as they pass through a concave lens?

A concave is thinner in the middle than the edges. They diverge, so the light rays never meet each other.

Describe the shape of a convex lens. What happens to parallel rays as they pass through a convex lens?

It is thicker in the middle than at the edges. The light rays meet and converge.

What two reasons makes the convex lens’ ability to bring light rays together useful?

It collects the light, and it forms a real image.

What is the one drawback to convex lenses?

The formation of an image depends on how far the object is from the lens.

What kind of image is formed when an object is placed at the focal point of a convex lens?

A real image, because the light rays meet together so you can now project the image.

How can our eyes see an object?

By light hitting our eyes.

Why can your eyes see what is directly in front of you but not what is around a corner?

Our eyes are able to see an object only if light is emitted from the object or bounces off it. Since light travels in straight lines from its source, there must be a direct path for light to strike your eyes to make vision possible.

What was Pythagoras’ theory about how we see? What was the problem with his theory?

Pythagoras’ theory was that light travelled from our eyes. The problem was that if we had light from our eyes we would be able to see in the dark.

What did Euclid discover when he shined a beam of light onto a flat mirror?

The angle between the incoming beam and the mirror is equal to the angle between the reflected beam and the mirror. This is known as the law of reflection.

What did Euclid suggest about how light travels?

Light travels in straight lines.

What did Ptolemy discover about light?

how light beams bend when they go from air to glass, which is refraction.

Who was Al-Haytham and what was his explanation for how vision worked?

An Arabian scientist, He was the first person to accurately describe how light worked. He said that light bounces off an object to the eye.

Describe Sir Isaac Newton’s light experiment. What did he prove?

That white light is actually a mixture of different colors of light.

Which scientist determined the speed of light? How did he do it?

Ole Romer. He placed mirrors on the tops of mountains in California, and measured the distance between the two mirrors, which was 35.4 km.

What is the speed of light?

299,789 km/s

What are the four basic properties of light?

Light travels in straight lines, light can be reflected, light can bend, light is a form of energy.

Optical Device

A technology that uses light.

Microscope

An optical device used for viewing very small objects.

Telescope

Make distant objects bigger and closer.

Refracting telescope

Refracting telescopes have two lenes, one on each end of a long tube. The larger lens is the objective lens that gathers light and focuses the rays toward the eyepiece, which in turn allows you to see the object larger than it appears with the unaided eye.

Reflecting telescope

Reflecting telescopes use a large circular mirror that curves inward. This curved surface gathers light extremely well. Another mirror inside the telescope directs light to the eyepiece, which leads to your eye.

Binoculars

Two short refracting telescopes fixed together, used to see distant objects.

What device would allow you to study the stars and planets?

A telescope.

What two important characteristics about telescopes allow us to see so much when we look through them?

It contains a concave and convex lens.

Compare and contrast refracting telescopes and reflecting telescopes?

A reflecting telescope contains a mirror that curves inward, and hits another mirror which goes to the eyepiece. A refracting telescope has two lenses, one on each end of a long tube. The larger lens is the objective lens that gathers light and focuses the light to the eyepiece, which makes the object larger.

What are binoculars? Name one advantage and one disadvantage about binoculars when compared to telescopes.

Two short refracting telescopes fixed together, used to see distant objects. They are more convenient, but not as strong as the telescopes.

Pupil

Allows light to enter your eye.

Aperture

Like the pupil, and allows light to enter a camera.

Iris

Circular band of muscle, expands and contracts to change the pupil.

Diaphragm

Like the Iris, changes the aperture to let in more or less light.

Shutter

Acts as a set of door that open when you press a button to take a picture, the longer the shutter remains open, the more light goes through camera to strike the film.

Retina

Thin layer covered with light receptor cells.

Rods

Highly sensitive to low levels of light, therefore can function in very low light.

Cones

Detect color, cannot function in low light, so all you see are shades of grey.

Optic nerve

Light is converted into electrical impulse which is transmitted to the brain by the optic nerve.

Film

Like the retina, film captures light and converts it into an image.

How does light get into your eye? How does this compare to a camera?

First, light passes through the pupil which is like the aperture of the camera, both allow light to pass through. Then it goes through the lens which changes shape to increase or decrease the quality of the image you see. Then, it moves to the back of the eye to the optic nerve which transmits the picture to your brain. The optic nerve is like the film in the camera.

What controls the size of the hole (pupil) in your eye? How does this compare to a camera?

The Iris, it is like the Diaphragm in the camera.

The iris regulates the amount of light that enters the eye. Describe how this behavior changes in dim light compared to bright light.

In dim light, it contracts so the pupil expands so more light can go through, in bright light, the iris expands to make the pupil smaller so less light goes through.

How does a camera shutter work?

It is like a set of doors, the longer the shutter stays open, the more light enters the camera to the film.

Name and describe the two types of photoreceptors.

Rods - sensitive to low levels of light, can function in low light.

Cones - Detects color, can't function in low light so it makes the dark look shades grey.

Once light strikes the retina and photoreceptors are stimulated, how does the message get to your brain? How does this compare to light striking film in a camera?

It goes through the optic nerve which is like the film in the camera.

Near-sightedness

A common vision condition where distant objects appear blurry while close ones can be seen clearly, caused by an elongated eyeball or overly curved cornea.

Farsightedness

A vision condition where close objects appear blurry while distant ones can be seen clearly, caused by a shortened eyeball or under-curved cornea.

How does laser eye surgery reshape the cornea of the eye?

The surgeon cuts a sliver of the eye and folds it and reshapes it with a laser so the shape of the eye can now direct the bending of light better to go into the retina.

Camera eyes

Refers to an eye containing a cornea, lens, and retina.

Nocturnal

Animals that are awake at night.

Compund eyes

Insects and crustaceans have these type of eyes which have a long tube at the end of the eyes.

Ommatidium

Long tube with a lens and optic nerve.

What structures in the eye are part of camera eyes? What types of animals have camera eyes?

Cornea, lens, and retina. Octopus, snake, fish, and any animal with backbone animals.

Describe fish eyes and how they are adapted to help them survive in their aquatic environment.

Fishes have camera eyes like humans, but they have a big round lens so they can see all around them, so they don't have to move their head.

How do the cones in birds' eyes differ from human eyes?

Birds have 5 types of cones, rather than humans only have 3. ( Red, green, and blue)

How do the eyes of nocturnal vertebrates allow them to collect as much light as possible?

They have really big pupils to allow in as much light as possible.

Describe how the eye of an invertebrate, such as an octopus, may compare to a human eye.

Octopus’ have camera eyes like humans, but instead of their lens changing shape, it stays the same and moves toward or away from the retina.

What are compound eyes made of? What do these individual units look like?

Many ommatidium (long tubes) grouped together. Each tube has its own lens and optic nerve fibers.

What makes the compound eye excellent at detecting any motion?

They have convex lenses which help them see all directions.

What are some drawbacks to the compound eye?

since they see many pictures, it's hard to form one single picture.