Discrete wavelengths of light are emitted by an excited gas because
a. the speed of light is constant in a given medium.
b. light can behave either as a wave or as a particle.
c. electron energy levels are quantized.
d. the intensity of radiation is proportional to the second power of the frequency.
c
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What was one of the first observations that hinted at limitations in Newton's theory of gravity?
A) deviations in the motion of the planet Uranus in the sky B) deviations in the motion of the planet Mercury in the sky C) shifts in position of stars close to the Sun during solar eclipses D) failure to explain why all objects fall at the same rate in a gravitational field
Light travels ________ in water than in air.
A. faster B. slower C. perpendicular to D. at the same speed
Which of the following hypothetical observations, if true, would disprove a prediction of the Big Bang theory?
A) the discovery that the temperature of the universe is only 2.73 K B) the discovery of a galaxy moving toward us C) the discovery of two galaxies at the same distance, moving away with slightly different speeds D) the discovery of a galaxy with 30% helium abundance E) the discovery of a galaxy with 10% helium abundance
A runner runs around a track consisting of two parallel lines 96 m long connected at the ends by two semicircles with a radius of 49 m. She completes one lap in 100 seconds. What is her average velocity?
A) 2.5 m/s B) 5.0 m/s C) 10 m/s D) 0 m/s E) 1.3 m/s