A ruby laser beam (? = 694.3 nm) is sent outwards from a 2.7-m diameter telescope to the Moon, 384,000 km away. What is the radius of the big red spot on the Moon?
a. 500 m
b. 250 m
c. 120 m
d. 1.0 km
e. 2.7 km
c
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In ancient times, constellation boundaries were well defined
a. True b. False Indicate whether the statement is true or false
Determine the heat transfer area requirements of Problem 10.40 if (a) 1-2 shell and tube, (b) an unmixed crossflow, and (c) a parallel flow heat exchanger are used, respectively.
GIVEN
• An air-to-gas heat exchanger
• Entering temperatures
? Ta,in = 350°C
? Tg,in = 700°C
• Mass flow rates: ma = mg = 5 kg/s
• Specific heats: cpa = cpg = 1.05 kJ/(kg K) = 1050 J/(kg K)
• Overall heat transfer coefficient (U) = 75 W/(m2 K)
FIND
The heat transfer area (A) as a function of the effectiveness (e) for (a) A 1-2 shell and tube heat exchanger (b) An unmixed crossflow heat exchanger (c) A parallel flow heat exchanger
ASSUMPTIONS
• For case (a) the air is in the tubes
SKETCH
A soap bubble has an index of refraction of 1.33. What minimum thickness of this bubble will ensure maximum reflectance of normally incident 530. nm wavelength light?
What will be an ideal response?
An electron is bound in an infinite well (a box) of width 0.10 nm. If the electron is initially in the n = 8 state and falls to the n = 7 state, find the wavelength of the emitted photon
(c = 3.00 × 108 m/s, h = 6.626 × 10-34 J ? s, mel = 9.11 × 10-31 kg)