A small gas laser of the type used in classrooms may radiate light at a power level of 2.0 mW. If the wavelength of the laser light is 642 nm, how many photons does it emit per second? (c = 3.0 × 108 m/s, h = 6.626 × 10-34 J ? s)
What will be an ideal response?
6.5 × 1015
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What is happening deep inside a star while it expands into a subgiant?
A) It is fusing hydrogen to produce helium in the core. B) It is fusing hydrogen to produce helium in a shell around the core. C) It is fusing helium to produce carbon in the core. D) It is fusing helium to produce carbon in a shell around the core. E) It is not fusing any element; it is contracting and heating up.
A bit of matter that enters Earth's atmosphere and survives to reach the ground is called
a. a meteor. b. a meteoroid. c. a meteorite. d. a minor planet. e. an asteroid.
A 40.0 cm long organ pipe is filled with air and is open at both ends. The velocity of sound in air at 0
is 331 m/s. If the temperature of the air decreases by 10
then what is the frequency of the fundamental mode?
A. 394 Hz B. 406 Hz C. 462 Hz D. 506 Hz E. 544 Hz
What do we call the effect of an increase in the amplitude when a periodic force is applied to a system at its natural frequency?
a. oscillation b. periodicity c. resonance d. vibration e. cycle