A ____ is believed to occur when energy, stored in a twist in the solar magnetic field above a sunspot, is suddenly released
a. solar flare
b. supergranule
c. spicule
d. coronal hole
e. none of the above
A
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Which kind of telescope and which instrument or technique are shown?
a. optical, CCD
b. infrared, array detector
c. optical, adaptive optics
d. radio, interferometry
including a contact resistance of 0.1 K/W at each of the interfaces. but assume that instead of surface temperatures, the given temperatures are those of air on the left and right sides of the wall and that the convective heat transfer coefficients on the left and right surfaces are 6 and 10 W/(m2K), respectively.
GIVEN
• Composite wall
• Thermal conductivities
? kA = 70 W/(m K)
? kB = 60 W/(m K)
? kC = 40 W/(m K)
? kD = 20 W/(m K)
• Air temperatures
? Left side (TA?) = 200°C
? Right side (TD?) = 50°C
• Contact resistance at each interface (Ri) = 0.1 K/W
• Convective heat transfer coefficients
? Left side ( cA h ) = 6 W/(m2 K)
? Right side ( cD h ) = 10 W/(m2 K)
FIND
(a) Rate of heat transfer through the wall (q) (b) Temperatures at the interfaces
ASSUMPTIONS
• One dimensional, steady state conduction
SKETCH
You need 14 W of infrared laser light power with wavelength 1270 nm to bore a hole in a diamond. How many downward atomic transitions per second must occur in the laser if all of them result in light directed onto the diamond?
(c = 3.00 × 108 m/s, h = 6.626 × 10-34 J ? s) A) 8.9 × 1019 B) 8.9 × 1018 C) 5.9 × 1019 D) 2.7 × 1018
What principle is responsible for the fact that certain sunglasses can reduce glare from reflected surfaces?
A) refraction B) reflection C) polarization D) diffraction E) total internal reflection