Subelement A: RADAR Principles – 10 Key Topics – 10 Exam Questions – 8 Drawings— Topic 2: Distance and Time
Question 8-2A1
Element 8 (RADAR)A radio wave will travel a distance of three nautical miles in:
Explanation
Radio waves travel at the speed of light. In a vacuum (and approximately in air), this speed is $3 \times 10^8$ meters per second.
To calculate the time it takes for a radio wave to travel three nautical miles, we first convert the distance to meters. One nautical mile is defined as 1852 meters.
So, 3 nautical miles = $3 \times 1852 \text{ meters} = 5556 \text{ meters}$.
Now, using the formula Time = Distance / Speed:
Time = $5556 \text{ meters} / (3 \times 10^8 \text{ meters/second})$
Time = $0.00001852 \text{ seconds}$
To express this in microseconds (where 1 microsecond = $10^{-6}$ seconds):
Time = $0.00001852 \times 10^6 \text{ microseconds} = 18.52 \text{ microseconds}$.
This value closely matches option D, 18.51 microseconds. Option A, 6.17 microseconds, is approximately the travel time for one nautical mile. The other options do not correspond to the correct calculation.
Related Questions
8-29D5 In a raster-type display, the electron beam is scanned:8-29D6 Select the statement, which is most correct regarding a raster scan display.8-2A2 One RADAR mile is how many microseconds?8-2A3 RADAR range is measured by the constant:8-2A4 If a target is 5 miles away, how long does it take for the RADAR echo to be received back at the antenna?