A laser emits light of wavelength 463 nm during a brief pulse that lasts for 25 ms and has a total energy of 1.2 J. How many photons are emitted in that single pulse? (c = 3.00 × 108 m/s, h = 6.626 × 10-34 J ? s)
A) 2.8 × 1018
B) 6.9 × 1019
C) 3.4 × 1019
D) 1.1 × 1017
E) 2.2 × 1017
Answer: A
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A) 1.75 hours B) 1.25 hours C) 1.15 hours D) 1.00 hours E) 1.45 hours
The heating element of a toaster is a 5.4-m length of nichrome wire of diameter 0.48 mm. The resistivity of nichrome at the operating temperature of the toaster is 1.3 × 10-6 ? ? m. The toaster is designed to operate at a voltage of 120 V
How much power does it draw in normal operation? A) 370 W B) 360 W C) 380 W D) 400 W E) 410 W
Most of the elements found on Earth were created
A. in the first few million years of the Earth's existence B. within a star C. in the Big Bang D. in a supernova explosion
The low-pressure center of a hurricane is called the ______________
Fill in the blank(s) with correct word