Straight Paths
How does light travel through air when nothing redirects it?
Light travels in a straight line.
What is the term for light bouncing off a surface?
Reflection.
What is the name for light changing direction as it
passes between materials?
Refraction.
A black surface takes in light energy. Name the
behavior.
Absorption.
True or false: your eyes send light toward objects so
you can see them. Correct it if false.
False. Light from objects enters your eyes.
A flashlight shines through three holes onto a wall. What must be true about the holes?
They must line up with the flashlight and the spot on the wall.
Which gives a clearer reflected image: a smooth mirror or a rough cloth?
A smooth mirror.
A straw looks bent where it enters a glass of water. What causes it to look bent?
Refraction. Light changes direction as it passes between water and air.
A clear window is transparent, and a wooden door is opaque. How does each affect light?
The transparent window lets light pass through. The opaque door blocks light from passing through.
A mirror sends light in a new direction. Is that
reflection or refraction? Explain.
Reflection: the light bounces off the mirror rather than passing into another material and bending.
A thick book blocks a flashlight beam. Why does a shadow form behind it?
The opaque book blocks the direct light path, so less light reaches the area behind it.
A light shines on your backpack. How does the light travel so you can see the backpack?
Light travels from the light source, reflects off the backpack, and enters your eyes.
Light source > Backpack > Eyes
Why can a magnifying lens change how large an
object appears?
Its curved surfaces refract light, changing the light paths that reach your eyes.
Name the main behavior in each: a mirror, a curved
lens, and a dark surface taking in light.
Mirror: reflection
Lens: refraction
Dark surface: absorption
A student says a submerged stick is broken because
it looks bent. Explain why this is not proof.
Refraction can change the apparent position of the
underwater part even when the stick is straight.
A student says that light will follow a curved cardboard tube with no mirrors. Correct the claim.
Light does not follow the curve on its own. Its straight path is blocked by the tube.
A flashlight shines on a mirror at an angle. What happens to the light?
A. It passes straight through the mirror.
B. It bounces off the mirror in a new direction.
C. It stops moving when it hits the mirror.
D. It bends around the mirror.
B. The light reflects off the mirror.
A pool floor looks more shallow than it really is when
viewed at an angle. Explain.
Light from the floor refracts as it moves from water to air, making the floor appear in a different position.
Why can you see both the room outside a window
and a faint reflection of yourself in it?
The glass transmits some light and reflects some light.
Explain why light can change direction at glass
even though light travels in straight paths.
Light travels straight within a uniform material. At a
boundary between materials, refraction can change its direction.
A beam of light needs to turn a corner. Name a material that could redirect it and the behavior involved.
A mirror can redirect the beam by reflection. The beam travels straight between reflections.
A mountain appears upside down in a calm lake. Explain the light path to your eyes.
Light reflects from the mountain, then from the water surface, and enters your eyes.
A student says, “Light only bends when it enters water, not when it leaves.” Is the student correct? Explain.
No. Light can bend both when it enters water from air and when it leaves water and enters air. This is refraction.
Which behavior bends sunlight as it enters and
leaves raindrops, helping form a rainbow? What
causes the bending?
Refraction. Light changes speed between air and water. Different colors bend by different amounts. Reflection
inside the drops also helps form the rainbow.
A spoon looks shifted where it enters water. Give a
two-part scientific explanation.
The behavior is refraction. Light from the submerged part changes speed and direction as it moves from water into air, changing where that part appears.