The intensity of a 50-dB whistle is doubled. What is the new decibel level?
a. 50 dB
b. 47 dB
c. 53 dB
d. 100 dB
c
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Type Ia and Type Ib supernovae both involve binary star systems
a. True b. False Indicate whether the statement is true or false
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)
The figure shows a cross section of three parallel wires each carrying a current of 5.0 A out of the paper. If the distance R = 6.0 mm, what is the magnitude of the magnetic force on a 2.0-m length of any one of the wires?
a.
2.5 mN
b.
3.3 mN
c.
2.2 mN
d.
2.9 mN
e.
1.7 mN
Explain two methods that could be used to find the spring constant of a spring experimentally