What is the parallax angle for Proxima Centauri, which is Earth's nearest star at 4.3 ly?
The earth's orbit has a mean radius of 1.5 108 km, and 1 ly = 9.46 1015 m.
A) 1.2 10-7 degrees B) 2.1 10-7 degrees
C) 1.2 10-14 degrees D) 2.1 10-4 degrees
Question 2
A light source radiates 60.0 W of single-wavelength sinusoidal light uniformly in all directions. What is the amplitude of the electric field of this light at a distance of 0.400 m from the bulb?
(0 = 8.85 10-12 C2/N m2, 0 = 4 10-7 T m/A, c = 3.00 108 m/s)
A) 162 N/C B) 52.9 N/C C) 212 N/C D) 150 N/C E) 82.1 N/C
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