Exam 4: Atomic Physics and Spectra

The Doppler effect is the

Hydrogen gas emits a strong spectral line of red light with a wavelength of 656.3 nm (the Balmer $\alpha$ line). This emission line is seen in the spectrum of a distant quasar but at a wavelength of 721.9 nm. Applying Doppler's relationship, how fast is this object moving with respect to Earth, in terms of the velocity of light, c?

When electromagnetic radiation (e.g., light) is Doppler-shifted by motion of the source away from the detector, the measured

The star alpha Proxima Centauri, the nearest star beyond the Sun, is 22 km closer to the Sun every second. This motion of alpha Proxima Centauri toward the Sun is an example of

Proper motion is the motion

The proper motion of a star or other object is measured by

Because of the Doppler effect, the sound of the engines of an aircraft that flies past an observer

The wavelength in the middle of the yellow part of the spectrum is 575 nm. What surface temperature would the Sun have if its peak were in the middle of the yellow?

The spectrum of sunlight, when spread out by a spectrograph, has which characteristic appearance?

How do the nuclei of the carbon ions C III and C IV differ from each other?

The chemical makeup of a star's surface is usually inferred by

The sodium D lines are a closely spaced pair of spectral lines in neutral sodium. They are present as absorption lines in the spectrum of the Sun's photosphere because of traces of sodium there. What would one expect to see if sunlight is passed through a cool sodium vapor in the laboratory and then observed with a spectroscope?

Suppose that a particular sample of wood contains 10²⁰ atoms of the radioactive isotope ¹⁴C. The half-life of ¹⁴C is about 6000 years. Approximately how long will it take for all the ¹⁴C atoms to decay to ¹⁴N?

An astronomer plots the intensity of the radiation emitted from an opaque object at a certain temperature versus its wavelength. As the object's temperature increases, the total amount of energy emitted all across the spectrum increases as the fourth power of the temperature. This is an illustration of

The average temperature of Mars is less than that of Earth. What would be the relative wavelengths of the peak emissions of the spectra from these planets?

An astronomer begins with an object at a certain temperature, and increases its temperature by an amount $\Delta$ T. For which one of these values of $\Delta$ T will the final temperature of the object be LOWEST?

The light from a small amount of a particular chemical element, when heated in a flame, is found to consist of a

Atoms of hot hydrogen gas will emit the Balmer series of spectral lines at visible wavelengths when the electrons fall from all higher atomic energy levels to the

The star P Cygni (in the constellation Cygnus, the Swan) is surrounded by an extensive low-density atmosphere. It has a bright, continuous spectrum with many narrow, dark absorption lines and a few bright emission lines. The bright, continuous part of the spectrum is produced by

By what factor does the total energy emitted per unit time at all wavelengths from an opaque, perfectly absorbing object increase if its temperature increases by a factor of 3 (e.g., approximately from room temperature to 900 K)?