Describe the difference between a real and a virtual image
A real image can be focused on a screen, whereas a virtual image cannot. The
observer must look into a lens or mirror to see a virtual image.
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Relate the formation of Mercury's scarps to its differentiation
What will be an ideal response?
Spherical Mirrors: An object that is 47.5 cm tall forms an image that is 38.6 cm tall and 14.8 cm from a spherical mirror. How far is the object from the mirror?
A. 124 cm B. 47.6 cm C. 18.2 cm D. 12.0 cm
Solar One, located near Barstow, CA, was the first large-scale (10 MW electric) solar- thermal electric-power-generating plant in the United States. A schematic diagram of the plant is shown below. The receiver may be treated as a cylinder 7 m in diameter and 13.5-m-tall. At the design operating conditions, the average outer surface temperature of the receiver is about 675°C and ambient air temperature is about 40°C. Estimate the rate of heat loss, in MW, from the receiver—via natural convection only—for the temperatures given. What are other mechanisms by which heat may be lost from the receiver?
GIVEN
• A vertical cylinder in air
• Height of cylinder (L) = 13.5 m
• Diameter (D) = 7 m
• Surface temperature (Ts) = 675°C
• Ambient air temperature (T?) = 40°C
FIND
(a) The rate of convective heat loss (qc) in MW
(b) What other mechanisms for heat loss exist?
ASSUMPTIONS
• Air is still
• Surface temperature is uniform and constant
PROPERTIES AND CONSTANTS
for dry air at the mean temperature of 357.5°C
Thermal expansion coefficient (?) = 0.00160 1/K
Thermal conductivity (k) = 0.0461 W/(m K)
Kinematic viscosity (?) = 58.1 × 10–6 m2/s
Prandtl number (Pr) = 0.72
When a metal surface is illuminated with light of wavelength 437 nm, the stopping potential for photoelectrons is 1.67 V
(c = 3.00 × 108 m/s, h = 6.626 × 10-34 J • s, e = - 1.60 × 10-19 C, 1 eV = 1.60 × 10-19 J, mel = 9.11 × 10-31 kg) (a) What is the work function of the metal, in eV? (b) What is the maximum speed of the ejected electrons?