Physics quiz Chptr 5
Which of the following can astronomers determine from the spectrum of an object?
- speed toward or away from an observer - temperature - composition
The nature of light is rather unique: It acts like both a particle (called a photon) and a wave that can propagate energy even through empty space.Navigate to the interactive figure in Section 2 of this animation, as shown below, to see how changing the amplitude, wavelength, speed, and frequency of a light wave affects its properties .Choose all of the effects that would automatically happen if the wavelength of light were increased.
- The energy of the light would decrease. - The frequency of the light would decrease
Following the invention of the telescope, astronomers were able to measure the speed of light by observing Jupiter's moons passing behind Jupiter in their orbit and becoming eclipsed. Study the figure, which shows how someone on Earth can view Jupiter's moon's eclipses when Earth is closer to or farther from Jupiter, and determine which of the following are correct.
If light has infinite speed, an eclipse would be seen to happen at the same time regardless of how far away Earth is from Jupiter.- If light has finite speed, it would take longer for it to travel from Jupiter to Earth when Earth is farther from Jupiter.
In a vacuum, light travels 300,000 km every second. Examine the following figure, which shows how long it takes for light to travel particular distances, and then scroll down to the question at the end. Based on the time frames given in the above figure, which of the following are implications of the finite speed of light?
If the light of the Sun were suddenly extinguished, we wouldn't notice it from Earth for over 8 minutes.- When we gaze at the Andromeda Galaxy, we are looking back in time to the way it used to appear millions of years ago.- There would be a noticeable delay in communications at the speed of light between Earth and astronauts on the Moon.
Changing the wavelength of visible light changes its color. If the wavelength is decreased or increased outside of the range of wavelengths our eyes can detect, the light becomes invisible to us, but it is still fundamentally light. Examine the figure, which shows the entire electromagnetic spectrum and includes all types of light as a function of wavelength.Given what you learned from the figure, rank these types of light in order of increasing energy.
[1 being Lower energy and 6 being Higher energy]1. Radio 2. Infrared 3. Orange 4. Green 5. Ultraviolet 6. Gamma ray
When you turn on a lightbulb in a room, the entire room appears to flood with light at the same time. Your eyes cannot perceive light originating at the bulb and then moving outward from it. This either means that light has infinite speed (appears everywhere instantaneously), or it moves so fast that it is difficult to tell the difference. How might you improve your chances of detecting the motion of light if it moves at finite speed?
move farther away from the light source
Observations of excited gas in the lab show that every element, molecule, and ion has its own unique set of possible electron energy levels, as shown in the emission spectra below. Based on this fact, what can we find from the wavelengths of absorption lines seen in the spectrum of a star?
the composition of any gas between the light-emitting "surface" of the star and the observer
