Exam 4: Atomic Physics and Spectra

Stars A and B have the same radius, but the spectrum of star A peaks at a wavelength of 500 nm, whereas star B's spectrum peaks at 1000 nm. What is the ratio of the Kelvin temperature of the surface of star A to the Kelvin temperature of the surface of star B?

The age of the solar system has been dated rather precisely to 4.57 billion years. What method was used to determine this number?

Spectral lines are of particular importance in astronomy because

Suppose that at some time a particular sample of radioactive material contains N radioactive atoms (e.g., N might be 1 billion radioactive atoms). How many radioactive atoms will be left after 3 half-lives have passed?

The angular motion of a star across the celestial sphere is a measure of its

What is the main reason that astronomers (and other scientists) almost always use the Kelvin (absolute) temperature scale rather than the Celsius or Fahrenheit scales?

The laws governing the energy flux F and wavelength of maximum intensity $\lambda$ _max of emitted radiation from a hot, dense body whose temperature is T (where $\sigma$ and a are constants) are given by

The majority of the mass of ordinary matter resides in the

On the absolute Kelvin temperature scale, the temperature of freezing water is about

Two heated spheres are at the same temperature, but one sphere has twice the radius of the other. The flux emitted from the larger sphere is

What property of helium allowed scientists to first discover its existence?

The dark absorption lines in the solar spectrum are caused by

The neutron is the electrically neutral particle that, along with the proton, makes up the atomic nucleus. The mass of the neutron, compared with that of the proton, is

The person who discovered the atomic nucleus was the

Pieces of metal are heated by varying amounts in a flame. The hottest of the pieces will be the one that shows MOST prominently which color?

Two perfectly absorbing spheres have radii of R and 3R. Both are held at the same temperature. The flux of radiant energy emerging from each square meter of the larger sphere is

What is the half-life of a sample of matter containing a radioactive element?

In the revolution that overtook physics around 1900, the assumption that Planck made in order to solve the problem concerning the spectrum of radiation emitted by a hot blackbody was that radiation was

The New Zealand physicist Lord Rutherford and his colleagues in England demonstrated the existence of the very small but massive nucleus inside every atom in which crucial experiment?

How many electrons surround the nucleus of a neutral atom of iron, which has an atomic number of 26?