Energy Density: A 4.4 × 1014 Hz laser emits a 2.1 ?s pulse that is 5.0 mm in diameter. The energy density in the beam is 0.24 J/m3. How many wavelengths are there in the length of the beam? (c = 3.0 × 108 m/s, ?0 = 4? × 10-7 T ? m/A, ?0 = 8.85 × 10-12 C2/N ? m2)
A. 9.2 × 108
B. 2.8 × 109
C. 2.8 × 108
D. 9.2 × 109
E. 2.8 × 1010
Answer: A
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A. It stays the same. B. It doubles. C. It quadruples. D. It halves. E. It increases by a factor of 5.66.
A photosensitive surface is illuminated with both blue and violet light. The light that causes the greater number of ejected electrons is
A) blue light. B) violet light. C) both eject equal numbers. D) need more information
Calculate an estimate of the range of a hypothetical force with the proton as the virtual exchange particle. (c = 3.00 × 108 m/s, h = 6.626 × 10-34 J ? s, mproton = 1.67 × 10-27 kg)
A) 6.7 × 10-25 m B) 2.1 × 10-16 m C) 6.0 × 10-8 m D) 1.5 × 10-15 m
For a plane to be able to fly clockwise in a horizontal circle as seen from above, in addition to exerting a force downwards on the air
a. it must be increasing its speed. b. it must exert a force on the air that is directed to the plane's left side. c. it must exert a force on the air that is directed to the plane's right side. d. it does not need to exert a force: it must only move the wing flaps out. e. it only needs to deflect the air without exerting any additional force on the air.