North Carolina RADAR State Practice Exam

Which materials typically do NOT absorb RADAR signals?

1. Sand and earth

2. Metal and concrete

3. Leaves and grass

4. Glass and plastics

The correct answer is: Metal and concrete

The correct answer highlights materials that generally do not absorb RADAR signals, which includes metal and concrete. These materials are primarily solid, dense, and have properties that reflect rather than absorb electromagnetic waves, including RADAR signals. Metal has a high conductivity, making it an excellent reflector of RADAR waves. Therefore, RADAR signals often bounce back when they encounter metal surfaces, enhancing detection capabilities in applications like surveillance or automotive RADAR systems. Similarly, concrete, while not as reflective as metal, has sufficient density and consistency to reflect some RADAR waves due to its structure and composition, using aggregates that can scatter signals effectively. In contrast, other materials listed tend to absorb RADAR signals to varying degrees. For example, sand and earth can store moisture, which can affect how RADAR signals are absorbed. Leaves and grass have organic compositions that can also contribute to absorption. Lastly, glass and plastics can have varying degrees of absorption based on their chemical makeup and structure, but they're generally more absorbent than reflective when it comes to RADAR.