Determine the amount of energy carried in 50 m of a 3.5-mW He-Ne laser beam if the cross-sectional area of the beam is 5.0 × 10^-6 m2
a. 2.9 × 10^–8 J
c. 0.024 J
b. 5.8 × 10^–10 J
d. 2.9 × 10^–10 J
B
You might also like to view...
A skater can spin faster by pulling her arms closer to her body or spin slower by spreading her arms out from her body. This is due to
A) the law of gravity. B) Newton's third law. C) conservation of momentum. D) conservation of angular momentum. E) conservation of energy.
Consider two copper wires. One has twice the length and twice the cross-sectional area of the other. How do the resistances of these two wires compare?
A) Both wires have the same resistance. B) The longer wire has twice the resistance of the shorter wire. C) The longer wire has four times the resistance of the shorter wire. D) The shorter wire has four times the resistance of the longer wire. E) The shorter wire has twice the resistance of the longer wire.
An ideal heat engine can have an efficiency of 1 if the temperature of the low temperature reservoir is
a. 0 K. b. 0°C. c. 0°F. d. 0°R. e. the same as the temperature of the heat source.
Compared to an identical ice cube exposed to air at room temperature, an ice cube wrapped in a wool blanket remain frozen for
1.less time. 2.the same length of time. 3.a longer time.