Unit Test: OpenSciEd Light and Matter

Question 1

When light hits a material and passes through it to the other side, what is this called?

Accepted Answer

Transmission

Question 2

Which part of the eye changes light into signals that travel along the optic nerve to the brain?

Accepted Answer

The retina

Question 3

A class used a light meter to test three materials. The same flashlight shined on each material, and the meter measured light on each side. Use the data table below. Which material behaves MOST like a one-way mirror?

Accepted Answer

Material 3, because it reflects and transmits light

Question 4

Figure: Amount of Light in Each Room (Model) — Bar graph showing Room A has 500 lux of light and Room B has 20 lux of light. — Room A: 500 lux · Room B: 20 lux A student modeled a one-way mirror between two rooms. The graph shows the amount of light in each room. Based on the data, what will a person in Room A most likely see when looking at the one-way mirror?

Accepted Answer

Mostly their own reflection, because reflected light from Room A is stronger

Question 5

At night, a person inside a brightly lit house looks at a regular glass window. The outside is dark. Which explanation BEST describes why the person sees their reflection instead of the yard outside?

Accepted Answer

The glass reflects a little indoor light, and this is stronger than the dim outdoor light

Question 6

A class used light meters to measure how much light three materials reflected and transmitted. The same flashlight was aimed at each material. Use the data table below to answer the question. Which conclusion is BEST supported by the data?

Accepted Answer

The one-way mirror both reflects and transmits a large share of light.

Question 7

A one-way mirror separates a brightly lit room from a dark room. A person in the bright room sees their own reflection, not the dark room. What is the BEST explanation?

Accepted Answer

The light reflected from the bright side is much stronger than the light transmitted from the dark side.

Question 8

Light reflects off a tree and enters a student's eye. Which sequence BEST describes what happens next so that the student sees the tree?

Accepted Answer

Lens focuses light → retina makes signals → optic nerve carries them to the brain

Question 9

A student shined white light on four shirts and recorded which colors of light each shirt reflected and absorbed. The student also wore a mask to hide the shirt color names. Use the data table below to answer the question. Which shirt would look BLACK, and why?

Accepted Answer

Shirt Z, because it absorbs all colors and reflects none to the eye.

Question 10

A student's model measured how much light passed through a window and how much reflected off it at different times. The measurements were taken inside a lit kitchen while it was dark outside after sunset. Figure: Light Reaching Viewer's Eyes at Night (Model) — Bar graph comparing light reaching a kitchen viewer's eyes at night: 120 lux reflected from the kitchen side of the window and 15 lux transmitted from the dark yard. — Reflected from kitchen: 120 lux · Transmitted from yard: 15 lux At night, a person in the kitchen sees their reflection in the window instead of the yard outside. Which statement BEST uses the graph to explain why?

Accepted Answer

Much more light from the kitchen reflects into the eye than light coming from the yard.

Question 11

In a light model, light usually travels in straight lines from a light source until it hits a material.

Accepted Answer

true

Question 12

The retina sends light itself through the optic nerve to the brain so the brain can see the image.

Accepted Answer

false

Question 13

A class used a light meter to test three materials. They shined the same flashlight on each material and recorded the results. Use the sample data below. Based on this data, the one-way mirror both reflects and transmits light.

Accepted Answer

true

Question 14

A one-way mirror separates a brightly lit room from a dark room. A person in the bright room mostly sees their own reflection. This happens because the reflected light from the bright room is stronger than the small amount of light transmitted from the dark room.

Accepted Answer

true

Question 15

At night, a student stands inside a lit house and looks at a regular window. They can see their reflection in the glass. If the outside became brighter than the inside, such as during the day, the student would most likely see the outdoors more clearly than their reflection.

Accepted Answer

true

Question 16

Name the THREE things that can happen when light reaches a material. For each one, give a short definition and one everyday example.

Accepted Answer

Reflection: light bounces off a surface, like light bouncing off a bathroom mirror. Transmission: light passes through a material, like sunlight going through a clear window. Absorption: light is taken in by the material and does not continue, like a black shirt absorbing sunlight and getting warm.

Question 17

Describe the path light takes for a person to see an object. In order, name the main parts of the eye that the light or signal moves through to reach the brain, and tell what each part does.

Accepted Answer

Light travels from a light source to the object and reflects off the object into the eye. The lens bends (refracts) the light and focuses it onto the retina. Receptor cells in the retina change the light into signals. The optic nerve carries these signals to the brain. The brain processes the signals so the person sees the object.

Question 18

A class used a light meter to test three materials. They shined a flashlight on each material and measured how much light was reflected back and how much light was transmitted through. The flashlight's brightness and distance stayed the same in every trial. (a) Which material reflected the most light, and which transmitted the most light? (b) Describe the pattern for the one-way mirror and explain how it compares to the other two materials. (c) Name one variable the class kept the same and explain why that mattered.

Accepted Answer

(a) The regular mirror reflected the most light (920 lux). Clear glass transmitted the most light (890 lux). (b) The one-way mirror both reflected light (510 lux) and transmitted light (430 lux). It falls in between the mirror, which only reflects, and clear glass, which mostly transmits. (c) The class kept the flashlight's brightness the same. This made it a fair test, so the differences in the readings came from the materials and not from the light source.

Question 19

A student modeled what happens to red light that hits objects of different colors. The graph shows the percent of red light each object reflected. Figure: Percent of Red Light Reflected (Sample Data) — Bar graph of the percent of red light reflected by four objects: red apple 85, white paper 90, green leaf 10, black cloth 4. — Red apple: 85 % · White paper: 90 % · Green leaf: 10 % · Black cloth: 4 % (a) Which object reflected the most red light, and which absorbed the most? (b) Use the data to explain why an apple looks red in white light. (c) Predict how the green leaf would look if ONLY red light shined on it, and explain your reasoning.

Accepted Answer

(a) White paper reflected the most red light (90%). Black cloth absorbed the most because it reflected only 4%. (b) White light contains many colors. The apple reflects most red light (85%) and absorbs most other colors, so mostly red light reaches our eyes and our brain sees red. (c) The leaf would look very dark or almost black. It reflects only 10% of red light and absorbs the rest, and there is no green light for it to reflect, so very little light reaches the eye.

Question 20

At night, Maya stands inside a brightly lit kitchen and looks at a regular glass window. She sees her own reflection instead of the dark yard outside. During the day, she can see the yard clearly through the same window.

Use your light-path model AND your eye-brain model to explain why Maya sees her reflection at night but sees the yard during the day. Include: (1) where the light comes from, (2) what the glass does to the light, and (3) how the amounts of light reaching her eye affect what her brain notices. Then propose ONE change Maya could make so she can see the yard at night.

Accepted Answer

Light from the kitchen lamps reflects off Maya and travels to the glass. The glass reflects a small part of this light back to her eyes and transmits the rest. At night, very little light comes from the dark yard, so only a weak amount of light is transmitted inward. The light reflected from the brightly lit kitchen is much stronger than the light coming from outside. Her retina sends stronger signals for the reflected image, so her brain notices her reflection. During the day, a lot of sunlight comes from the yard through the glass. This transmitted light is much stronger than the reflected kitchen light, so she sees the yard. This works just like a one-way mirror, where the brighter side sees a reflection. Maya could turn off the kitchen lights or turn on an outdoor light. Either change makes the outside brighter than the inside, so the transmitted light becomes stronger.

Question 21

Explain what each of these words means when light hits a material: reflect, transmit, and absorb. Give one everyday example for each.

Accepted Answer

When light reflects, it bounces off a surface, like light bouncing off a mirror. When light is transmitted, it passes through a material, like sunlight going through a clear window. When light is absorbed, it is taken in by the material and does not continue, like a black shirt getting warm in the sun.

Question 22

Describe the path light takes for you to see an object such as a book in a lit room. Name the parts of the eye the light passes through or reaches, and explain what happens once the light reaches the back of the eye.

Accepted Answer

First, light travels in a straight line from the light source to the book. The light reflects off the book and travels to my eye. It enters through the pupil, and the lens bends (refracts) the light to focus it on the retina. The retina changes the light into signals, and the optic nerve sends those signals to the brain, which makes sense of them so I see the book.

Question 23

A class used a light meter to test three materials. They shined the same flashlight at each material and measured how much light was reflected back and how much was transmitted through. Sample data from the class investigation: Describe the pattern in the data. Explain what the data tells you about how a one-way mirror is different from a regular mirror and clear glass.

Accepted Answer

The regular mirror mostly reflects light: 920 lux reflected and 0 lux transmitted. The clear glass mostly transmits light: 890 lux went through and only 80 lux reflected. The one-way mirror is different because it both reflects and transmits, with 510 lux reflected and 430 lux transmitted, so it splits the light about in half. This is why it can act like a mirror and a window at the same time.

Question 24

Figure: Diagram of a one-way mirror separating two rooms. Room A on the left is brightly lit with a ceiling lamp and a person standing in it. Room B on the right is dark with a person standing in it. Arrows show light from Room A's lamp hitting the person in Room A, and some of that light reflecting off the one-way mirror back into Room A while some passes through into Room B. Use the diagram to explain why the person in the bright Room A sees their own reflection, while the person in the dark Room B can see into Room A. Include ideas about reflection, transmission, and how the eye and brain respond to stronger and weaker light.

Accepted Answer

The person in Room A sees a reflection because the bright light in Room A bounces off them, hits the mirror, and a lot of it reflects back into their eyes. Only a tiny bit of light comes through from dark Room B, so the strong reflected light is what their retina and brain notice. The person in Room B can see into Room A because some of the bright light from Room A is transmitted through the coating into Room B. Room B has very little light to reflect, so the transmitted light from Room A is the stronger signal. The brain pays attention to the stronger light, so each person sees something different.

Question 25

At night, Maria stands inside her brightly lit kitchen and looks at the window. She sees her own reflection instead of the dark yard outside. During the day, she can easily see the yard through the same window.

Using what you learned about light and the one-way mirror, explain why the ordinary window acts like a mirror at night. Then design a simple test Maria could do to check your explanation. Name what she would change, what she would keep the same, and what results would support your idea.

Accepted Answer

At night the window acts like a mirror because glass reflects a small amount of light. The bright kitchen light reflects off Maria and the glass back to her eyes. Very little light comes in from the dark yard, so the reflected light is much stronger and her brain notices her reflection. During the day, the bright light from outside is transmitted through the glass and is stronger than the reflection. To test this, Maria could turn off the kitchen lights at night, or turn on a bright outdoor light. She would keep the same window, the same spot to stand, and the same time of night. If my explanation is correct, she would see the yard instead of her reflection when the outside is brighter than the inside.

Material	Light Reflected (lux)	Light Transmitted (lux)
Material 1	5	92
Material 2	88	2
Material 3	45	48

Unit Test: OpenSciEd Light and Matter

Part A: Multiple Choice

Part B: True / False

Part C: Short Answer

Part D: Essay / Extended Response

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