A parallel plate capacitor is constructed with Teflon (dielectric constant 2.1 ) between the plates. This 12.6 ?F capacitor has been charged to 1.5 volts. The Teflon is then pulled out (removed)
(a) What charge was originally stored?
(b) After removing the Teflon, what potential is across the plates?
(a) 19 ?C
(b) 3.2 volts
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Resistance and Resistivity: Which one of the following quantities is equivalent to 1 ??
A. 1 J/s B. 1 W/A C. 1 V ? A D. 1 V/A E. 1 A ? s
For an ideal radiator (hohlraum) with a 10-cm-diameter opening, located in black surroundings at 16°C, (a) calculate the net radiant heat transfer rate for hohlraum temperatures of 100°C and 560°C, (b) the wavelength at which the emission is a maximum, (c) the monochromatic emission at ?max, and (d) the wavelengths at which the monochromatic emission is 1 per cent of the maximum value.
GIVEN
• An ideal radiator (hohlraum) in black surroundings
• Radiator opening diameter (D) = 10 cm = 0.1 m
• Surrounding temperature (Ts) = 16°C = 289 K
• Hohlraum temperatures
- Th1 = 100°C = 373 K
- Th2 = 560°C = 833 K
FIND
(a) The net radiant heat transfer rate (qr)
(b) The wavelength at which the emission is maximum (?max)
(c) The monochromatic emission at ? max (E?max)
(d) The wavelengths at which the monochromatic emission is 1% E?max
SKETCH
PROPERTIES AND CONSTANTS
the Stephan-Boltzmann constant (?) = 5.67 × 10–8 W/(m2 K4)
Which of the following is not one of the three major categories of galaxies?
A) globular galaxies B) elliptical galaxies C) spiral galaxies D) irregular galaxies
How do earthquakes allow us to model the structure of Earth's core?
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