A laser pulse of duration 25 ms has a total energy of 1.4 J. If the wavelength of this radiation is 567 nm, how many photons are emitted in one pulse? (c = 3.00 × 108 m/s, h = 6.626 × 10-34 J ? s)
A) 4.8 × 1019 B) 3.2 × 1017 C) 9.9 × 1019 D) 4.0 × 1018 E) 1.6 × 1017
D
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The nichrome heating element in an electric drier operates on 240 V and generates thermal energy at the rate of 2.0 kW. The heating element shorts out and, in repairing it, the repairman shortens the nichrome wire by 10%
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Indicate whether the statement is true or false