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LenaWriter [7]
2 years ago
9

Dish-shaped reflectors are used to steer microwaves in order to establish communications links between nearby buildings. Those r

eflectors are often made from metal mesh. Why don't they have to be made from solid metal sheets
Physics
1 answer:
Ad libitum [116K]2 years ago
5 0

A "screen" or even just a set of parallel bars are highly reflective to electromagnetic waves as long as the open spaces are small compared to the wavelengths.

"Grid" dishes work fine ... with less weight and less wind resistance ... for frequencies below about 3 GHz. (Wavelengths of at least 10 cm.)

(I even worked on a microwave system in South America where huge grid dishes were used on a 90-mile link.)

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A mass hanging from a spring is set in motion and its ensuing velocity is given by v (t )equals 2 pi cosine pi t for tgreater th
lianna [129]

Answer:

2(maximum), -2(minimum), -2(maximum).

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V(t)= 2πcos πt--------------------------------------------------------------------------------(1).

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Applying the condition given, we have s(0)= 0.

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The mass moves to its highest positions at time,t=half(1/2=.5) and time,t=2.5.

Take note that;  sin(π/2) = sin(5π/2) = 1 .

Also, the mass moves to its lowest position at time,t=(3/2); also, sin(3π/2) = -1.

Therefore, we have that 2 maximum; -2 minimum and -2 maximum.

7 0
3 years ago
A teacher wants to perform a classroom demonstration that illustrates both chemical and physical changes. Which would be the bes
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