The filament in a light bulb has a diameter of 0.050 mm and an emissivity of 1.0. The temperature of the filament is 3000°C. What should be the length of the filament so it will radiate 60 W of power?
The Stefan-Boltzmann constant is 5.670 × 10-8 W/m2 · K4.
A) 11 cm
B) 9.4 cm
C) 8.6 cm
D) 7.2 cm
E) 5.9 cm
Answer: E
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a. 5.7° W of N b. 12° W of N c. 22° W of N d. 11° E of N
Planet W-70 has a radius of 2.48 × 107 m and an escape velocity of 23,300 m/s. What is the mass of W-70? (G = 6.67 × 10-11 N ? m2/kg2 )
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The dimensional equivalent of the quantity impulse in terms of the fundamental quantities (mass, length, time) is which of the following?
a. MLT?1 b. ML2T?2 c. MLT d. MLT?2
The wavelength of a wave multiplied by the frequency of the wave is the wave's
a. speed b. frequency c. wavelength d. amplitude e. loudness