Answer:
D. 4000 km
Explanation:
f = Frequency of wave that is being transmitted = 76 Hz
= Wavelength of wave that is being transmitted
v = The velocity of electromagnetic waves through air =
Velocity of a wave is given by
Hence, the approximate wavelength of the waves is 4000 km
The maximum amount of work performed is
Explanation:
The efficiency of a real heat engine is given by the equation:
(1)
where
is the temperature of the cold reservoir
is the temperature of the hot reservoir
However, the efficiency of a real heat engine can be also written as:
where
is the maximum work done
is the heat absorbed from the hot reservoir
can be written as
where
is the heat released to the cold reservoir
So the previous equation can be also written as
(2)
By combining eq.(1) and (2) we get
And re-arranging the equation and solving for , we find
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