In the critical density universe now proposed, the ratio of dark energy to matter is about
A) 1 to 5. B) 1 to 1. C) 10 to 1. D) 3 to 1. E) 1 to 100.
D
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Shell Radius: The distance between adjacent orbits in a hydrogen atom
A. increases with increasing values of n. B. decreases with increasing values of n. C. remains constant for all values of n. D. varies randomly with increasing values of n.
A proton (1.67 × 10-27 kg) is accelerated to 99.8% the speed of light. How much energy did the accelerator have to impart?
A) 14.8 GeV B) 13.9 GeV C) 38.9 GeV D) 7.52 GeV E) 223. GeV
On a bright and sunny day, the intensity of solar radiation on the Earth's surface is 1 000 W/m2 . If the average wavelength of the sunlight is 500 nm, how many photons are incident on a square meter of the Earth's surface per second?
The spectra of different elements can be distinguished because
a. they have the same spectral lines, but the lines are of different intensities. b. they have spectral lines in different positions. c. every element has one unique spectral line. d. none of the above