UNDER THE RADAR

Reflection is what happens when light bounces off matter.

RADAR SYSTEMS

REFLECTED LIGHT In reflected light, the angle of incidence always equals the angle of reflection. The normal is an imaginary line perpendicular to the reflective surface. Incident Ray Reflected Ray Angle of Incidence Instructor Notes: After students have completed the Mirror Reflection activity, have them compare their results with this diagram. Explain that the angle of incidence is always equal to the angle of reflection.

On a rough surface, the normal is constantly changing. REFLECTED LIGHT Light reflected off of a rough surface is scattered in many directions. On a rough surface, the normal is constantly changing. Incident Light Instructor Notes: After students have completed the Mirror Reflection activity, have them compare their results with this diagram. Explain that the angle of incidence is always equal to the angle of reflection.

RADAR SYSTEMS Radar systems have two components. The transmitter sends out radio waves. The receiver detects radio waves. Transmitter Receiver Instructor Notes: Show students this diagram of how a radar system works. Have students model this radar system with a laser pointer (transmitter), a mirror (reflecting target), and white paper (receiver). (Explain that the blue component in the diagram is the antenna, which both emits and receives waves.) Based on their model, students should explain how a radar system works.

RADAR SYSTEMS The receiver detects the reflected waves. The transmitter sends out radio frequency light. When the radio waves hit a reflecting target, they are reflected. Reflecting Target Transmitter Receiver Instructor Notes: After students have diagramed how they think a radar system works, show them this diagram. Explain that the radar system emits radio waves which are reflected by the target. The reflected waves are picked up by the receiver. Based on the direction in which the receiver is pointed and how long it takes for the radio waves to come back, the radar system can tell where the reflecting object is.

What would happen if standing between the radar and the target was… LOW APPROACH What would happen if standing between the radar and the target was… a mountain? Instructor Notes: Ask students to explain what would happen if a mountain is standing between the radar and the target. Would the radar see the target?

RADIO DRONES

RADIO DRONES What would happen if drones emitted radio signals directed at the radar system? Instructor Notes: Ask students to explain what would happen if drones emitted radio signals directed at the radar system. How would this affect radar function? Reflecting Target

CHALLENGE Absorption Redirection Jamming Instructor Notes: Present students with the challenge activity. Students will test how different materials absorb light, how different shapes affect the reflection of light, and how bright white light can affect the detection of light.r Absorption Redirection Jamming

CHALLENGE How do different materials absorb light? How do different shapes affect the reflection of light? And how does bright white light affect the detection of light? Instructor Notes: Present students with the challenge activity. Students will test how different materials absorb light, how different shapes affect the reflection of light, and how bright white light can affect the detection of light.