Radio communication and television
Answers are for parents and teachers.
1
The echo arrives after 260 μs. What is the distance in km?
39
2
The pulse lasts 4 μs. What is its length cτ in m?
1200
3
λ = 20 cm and τ = 4 μs. How many oscillations are in the pulse?
6000
4
How many times greater is the line-of-sight range for h = 400 m than for 100 m?
2
5
Why do we transmit a modulated high-frequency wave in radio instead of the sound frequency itself?
At low frequency the radiation is very weak (I ∝ ν⁴) and stations would mix; a high-frequency carrier radiates well and allows channels to be separated.