Why does the number of sunspots change over time?
A. The Sun's magnetic field changes in strength and shape with time.
B. The brightness of the Sun increases and decreases with time.
C. The temperature of the Sun increases and decreases over time.
D. The solar wind changes speed with time, obscuring them.
E. The number of sunspots does not change-the spots are simply on the other side.
Answer: A
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Why must lander probes on Mars be sterilized before launch?
A) to prevent terrestrial microbes hitching a ride on the probe and contaminating the Martian surface B) to prevent terrestrial microbes destroying the electronics in the probe during its passage to Mars C) to prevent Martian dust from building up on the probe on the surface D) to prevent Martian microbes from contaminating the lander probe
Assume that the brightness of an ohmic light bulb with resistance R is directly proportional to the power it dissipates. If we connect it to the plates of a charged capacitor with capacitance C at time t = 0, by what factor is it dimmer at time t = 2RC than its initial brightness?
A. 1/2 B. 1/4 C. 1/2e D. 1/e2 E. 1/e4 F. Some other factor (specify)
Which moon of Saturn has the surface with the widest range of ages? Why?
What will be an ideal response?
Although we don't know exactly when clusters, galaxies, or stars began forming, we do know that clusters came first, with galaxies and stars forming later
Indicate whether the statement is true or false