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.)
Answer:
Volume of wood is 68-50 = 18 cm³
Explanation:
<h2>Hope it helps you</h2>
Answer:
Ideal machines are said to have parts which are weightless , frictionless and strings if any are inextensible. Practical machines have parts which have weights, friction and it causes some loss of work done. So these are the differences between Ideal Machine and Practical Machines.
You can find the emf of the battery by using:
Q = CV.
Q = Charge in capacitor plates = 30μC
C = Capacitance of the capacitor = 30μF
V = Q/C = 30/30 = 1V
Ans: The emf of the battery = 1V.
