Answer:
a) 915 m
b) 0.15 W/
Explanation:
solution:
a) The wavelength of the microwaves electromagnetic wave is:
λ=
=
=0.025 m
the circular radar antenna acts like a circular aperture of diameter D will have a bright central maximum of diameter:
w=2.44λL/D
so at 30 km screen:
w=2.44λL/w
=2.44*0.025*30*10^3/2
=915 m
b)
The area of a beam at 30 km is:
A=
=
=
=
the average microwave intensity is equal to the ratio of the power of the antenna and area of the beam:
I=P/A
So at 30 km:
I=100*10^3/657*10^3
=0.15 W/
Answer:
one truck load is 2.5*1.5*1 = 3.75m^3
7/3.75 = 1.86 loads,
so 2 trips must be made.
Explanation: