Suppose You See Two Main-Sequence Stars of the Same Spectral

question 130

Multiple Choice

Suppose you see two main-sequence stars of the same spectral type.Star 1 is dimmer in apparent brightness than Star 2 by a factor of 100.What can you conclude? (Neglect any effects that might be caused by interstellar dust and gas. )

• A)Without first knowing the distances to these stars,you cannot draw any conclusions about how their true luminosities compare to each other.
• B)The luminosity of Star 1 is a factor of 100 less than the luminosity of Star 2.
• C)Star 1 is 100 times more distant than Star 2.
• D)Star 1 is 100 times nearer than Star 2.
• E)Star 1 is 10 times more distant than Star 2.

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Definitions:

AV Node

The atrioventricular node is an element of the heart's conduction system that regulates heart rate by decelerating the electrical impulse prior to its transfer from the atria to the ventricles.

Action Potential

Change in membrane potential in an excitable tissue that acts as an electric signal and is propagated in an all-or-none fashion.

Atria Contract

refers to the phase in the cardiac cycle when the atria (upper chambers of the heart) contract to push blood into the ventricles.

Plateau Phase

Prolongation of the depolarization phase of a cardiac muscle cell membrane; results in a prolonged refractory period.