101) Which type of star is maintained by the pressure of an electron gas?
(a) Main Sequence Star
(b) White Dwarf
(c) Neutron Star
(d) Black Hole
Answer: (b)
White dwarfs are stars supported by pressure of degenerate electron gas. i.e. in their interiors thermal energy kT is much smaller then Fermi energy Ep. We shall derive the equations of structure of white dwarfs, sometimes called degenerate dwarfs, in the limiting case when their thermal pressure may be neglected, but the degenerate electron gas may be either non-relativistic. somewhat relativistic. or ultra-relativistic.
102) Which of the following first hypothesized that the Earth orbited the sun?
(a) Alexander the Great
(b) Copernicus
(c) Socrates
(d) Tycho Brahe
Answer: (b)
Nicolaus Copernicus was a Renaissance mathematician and astronomer who formulated a model of the universe that placed the Sun rather than the Earth at the center of the universe.