Why is it that the quasars we see represent a time when the universe was younger?
What will be an ideal response?
Quasars have very large redshifts, corresponding to large cosmological distances. Since the light they emitted travels at a finite velocity, it must have left the quasar many billions of years ago.
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Which of the following statements about thermal radiation is always true?
A) A hot object emits more x-rays than a cool object. B) A hot object emits more radio waves than a cool object. C) A hot object emits more total radiation than a cool object. D) A hot object emits more total radiation per unit surface area than a cool object. E) A hot object emits less total radiation than a cool object.
Which of the following types of radiation has the greatest ability to penetrate matter?
a. Gamma rays b. Beta particles c. Alpha particles d. Protons
The SI unit of pressure is the pascal
Indicate whether the statement is true or false
Why do you hear thunder a substantial time after seeing a lightning flash?
a. The sound is produced later than the light is. b. Your eyes respond more quickly than your ears. c. The flash and thunder really are simultaneous, but the thunder lasts longer than the flash. d. Sound travels much more slowly than light.