A star is on the horizontal branch of the H-R diagram. Which statement is true?
A) It is burning only helium.
B) The star is contracting.
C) The star is about to return to the main sequence.
D) It is about to experience the helium flash.
E) It is burning both hydrogen and helium.
E
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What evidence is there that supernovae really have occurred?
A) Crab Nebula B) supernova remnants C) existence of heavy radioactive elements in nature D) observations of the actual explosions E) All of the above.
A camera lens that covers the film with a field of view that corresponds approximately to that of normal vision is referred to as a
A) normal lens. B) telephoto lens. C) wide-angle lens. D) zoom lens. E) digital lens.
Which one of the following IS NOT a characteristic of terrestrial planets?
a. low average density b. orbits inside the asteroids c. craters in old surfaces d. small diameters e. very few satellites
What is the maximum kinetic energy (in eV) of a photoelectron emitted from a surface whose work function is 5.0 eV when illuminated by a light whose wavelength is 200 nm?
a. 1.9 b. 1.2 c. 3.1 d. zero e. 6.2