Light and Sound Review 4/3/20

All light has a source, or something it comes from. And that source can be natural or artificial. Sources of natural light are the sun, other stars, lightning and fire. Some living things can even make their own light, like fireflies and jellyfish. Sources of artificial light are light bulbs, computer or TV screens and neon lights, to name a few.

The sun is our main source of light. All living things need energy from the sun to survive. Plants use sunlight to make their own food. Most animals need sunlight to warm their bodies. Sunlight even makes water move through the water cycle.

Which of the following is NOT true about sunlight?

• It moves water in the water cycle.

• It makes computer and TV screens bright.

• It helps plants make their own food.

• It keeps many animals warm.

Tags

NGSS.MS-ESS2-4

NGSS.MS-LS1-6

NGSS.MS-LS2-3

Light moves. It travels all the way from the sun or from other stars to the Earth. It travels from any source. That's why we can see it, because it travels into our eyes. Light travels in a straight line, and it travels very fast.

When light hits an object, some of the light reflects or bounces off. That's why we can see it. Mirrors reflect almost all the light that hits them.

Light moves and travels

• by reflecting off of our eyes.

• in a slow zigzag by bouncing off stars.

• quickly, in a straight line.

• from only one source—the sun.

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NGSS.MS-PS4-2

Light can also pass through some things. Light can easily pass through clear objects, like glass windows. That's why you can see through clear objects.

There are also some objects that let only some light pass through—stained glass windows and sunglasses, for example. They block some light and let other light pass through. So you can see through them, but not as well as you can see through clear glass.

Which of the following is an example of an object that would let only some light through?

• a full length mirror

• a clear raincoat

• a regular glass window

• a green plastic water bottle

Tags

NGSS.MS-PS4-2

Sometimes light hits an object, and it can't pass through it. The object blocks the light and keeps it from going to the other side. You can't see through objects like books, a refrigerator or a tennis shoe. If you made a sneaker out of glass, you could see through it, but it wouldn't be very comfortable.

We see shadows, or darker areas, when objects block the light. Have you ever made a shadow puppet on the wall? You can do that when there is one bright light aimed at a wall and you put your hand in front of it. The shadow is the shape of the thing that blocks the light.

Shadows are the shape of the thing that blocks the light

When you make a shadow puppet

• your hand creates the shadow by blocking part of the light.

• the light reflects off of your hand to create the shadow.

• all the light surrounding your hand is made brighter.

• the light passes through your hand to form the shadow.

Tags

NGSS.MS-PS4-2

All objects—dull or shiny—reflect light. Shiny objects just reflect light the best. In order to see something, a source of light must shine on the object, then that light reflects off the object into your eyes. Without this reflection, you would not see. That's why when it's "pitch black," you can't see anything—there's no light to reflect off any objects. Though shiny objects reflect light best, anything you can see is reflecting light.

What is the best evidence that you are experiencing “pitch blackness”?

• You can see shadows.

• The moon is visible in your window.

• You can't see any objects.

• The objects in the light are dull.

Tags

NGSS.MS-PS4-2

Sound is a type of energy, just like light, heat, motion and electricity. Sound is energy that people can hear. It’s produced by vibration. A vibration is a quick back and forth movement. If you pulled a rubber band between your fingers so that it made a “twang” noise, it would vibrate. That vibration produces a sound. For sound to travel, it needs a medium, or something with molecules, to carry it. Sound energy can travel underwater, in the air and through doors, walls and windows, too. But it cannot travel if there’s no matter to carry it, like in the vacuum of deep space.

Based on the passage, sound doesn’t travel in deep space because

• there is no energy in deep space.

• there is no light to see it in deep space.

• there are no molecules to carry it in deep space.

• there is no heat in deep space.

An echo is a sound wave that is reflected off of a surface and back to a listener. When sound waves meet a solid substance, the energy may be carried through that substance. Some of it might be absorbed into the substance. In some cases, some might also be reflected off the surface and bounce back. If you hear the same sound again, it’s an echo. Some animals, like bats and dolphins, use echoes to help them navigate. They create sounds and, based on the echoes, they can determine where things are in space. That’s called echolocation.

Which detail from the passage best explains why a friend’s voice might sound muffled if she calls to you through a closed door?

• “They create sounds and, based on the echoes, they can determine where things are in space."

• “In some cases, some might also be reflected off the surface and bounce back.”

• "That’s called echolocation."

• “Some of it might be absorbed into the substance.”

Tags

NGSS.MS-PS4-2

We can hear sound. Sometimes, we can see and feel it, too. If you strum on a guitar and look closely at the strings, you can see them vibrating. That vibration is the very sound you hear. If you put a piece of paper over a stereo, you can see the sound vibrating the paper. If you put rice on top of a drum and bang on the drum, you’d see the rice move. Want a simple way to feel sound? Put your hand on your throat and hum.

Which of the following is the best topic sentence for this passage?

• Sound moves in waves through a medium.

• A guitar is a musical instrument that has strings.

• There are three main components of the human ear.

• We can perceive sound with our senses.