Frank D. Drake, an investigator in the SETI (Search for Extra-Terrestrial Intelligence) program, once said that the large radio
telescope in Arecibo, Puerto Rico, can detect a signal which lays down only a picowatt of power over entire surface of the Earth. What is the power received by the radio telescope if the diameter of the antenna is300 m? What would be the power of the source at the center of our galaxy which couldprovide such a signal? The center of galaxy is 22000 light years away. Assume that source is radiating uniformly in all directions and that the Earth is a disk with the radiusof 6378 km.
1 answer:
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Answer:
critical clearing angle = 70.3°
Explanation:
Generator operating at = 50 Hz
power delivered = 1 pu
power transferable when there is a fault = 0.5 pu
power transferable before there is a fault = 2.0 pu
power transferable after fault clearance = 1.5 pu
using equal area criterion to determine the critical clearing angle
Attached is the power angle curve diagram and the remaining part of the solution.
The power angle curve is given as
= Pmax sinβ
therefore : 2sinβo = Pm
2sinβo = 1
sinβo = 0.5 pu
βo = ⁰
also ; 1.5sinβ1 = 1
sinβ1 = 1/1.5
β1 = = 41.81⁰
∴ βmax = 180 - 41.81 = 138.19⁰
attached is the remaining solution
The critical clearing angle = ≈ 70.3⁰
