A sphere of surface area 1.25 m2 and emissivity 1.0 is at a temperature of 100°C. At what rate does it radiate heat into empty space? (? = 5.67 × 10-8 W/m2 ? K4 )
A) 7.1 W
B) 0.71 mW
C) 1.4 kW
D) 9.9 mW
E) 3.7 W
C
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Protons are being accelerated in a particle accelerator. When the energy of the protons is doubled, their de Broglie wavelength will
A) increase by a factor of 4. B) increase by a factor of 2. C) decrease by a factor of 2. D) increase by a factor of . E) decrease by a factor of .
Which of the following transitions in hydrogen from an initial state (ni) to a final state (nf) results in the most energy emitted?
a. ni = 80, nf = 2 b. ni = 3, nf = 95 c. ni = 2, nf = 1 d. ni = 1, nf = 3
A sinusoidally varying potential difference has amplitude 170 V. What is its rms value?
1.170 V 2.120 V 3.0 4.-120 V 5.-170 V
Water flows into and out of the tank. If V = 8 m/s and Q = 0.02 m^3/s, the mass flux is nearest:
A) 6 kg/s
(B) 8 kg/s
(C) 10 kg/s
(D) 12 kg/s