Which of the following is not an observed characteristic of the cosmic microwave background?
A) It contains prominent spectral lines of hydrogen, the primary chemical ingredient of the universe.
B) It has a perfect thermal radiation spectrum.
C) Its temperature is the same everywhere, except for small variations at the level of 1 part in 100,000.
D) Its temperature is a little less than 3 Kelvin (3 degrees above absolute zero).
A) It contains prominent spectral lines of hydrogen, the primary chemical ingredient of the universe.
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On a weather map, an L depicts an area of low pressure. In this region, if the isobars are closely spaced around the low, the weather forecast calls for
A) cloudy skies and windy conditions. B) clear skies with light winds. C) warm temperatures with light winds. D) snow.
Any oscillating system for which the net restoring force is directly proportional to the displacement is said to exhibit simple harmonic motion
Indicate whether the statement is true or false
A typical source of infrared radiation is
A) magnetized particles vibrating in iron and certain other metals. B) charged particles moving within the nucleus. C) electrons moving along a metal antenna. D) thermal vibrations of molecules. E) electrons orbiting the nucleus in atoms.
What happens when two forces act in the same direction?
A. They cancel each other out. B. They are added together. C. They are subtracted. D. Their sum divided by two is the total force.