Which of the following persons reorganized the spectral classification scheme into the one we use today and personally classified over 400,000 stars?
A) Annie Jump Cannon
B) Williamina Fleming
C) Cecilia Payne-Gaposchkin
D) Henry Draper
E) Edward Pickering
A
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Which of the following is an example of ordinary (baryonic) matter?
A) you B) photons of light C) electrons and positrons produced by pair production D) weakly interacting massive particles (WIMPs) E) neutrinos
The speed of light in a certain medium is 2.2 × 108 m/s. What is the index of refraction of this medium?
A) 1.0 B) 1.2 C) 1.4 D) 1.6 E) 1.8
To subtract a vector from another vector:
a. add the two vectors and make the result negative. b. draw an arrow from the tail of the first vector to the head of the second. c. draw an arrow from the head of the first vector to the tail of the second. d. turn the arrow you are subtracting around, and then add. e. put one on top of the other, put a minus sign by the lower one, and then subtract as if they were numbers.
Wire B has twice the length and twice the radius of wire A. Both wires are made from the same material. If wire A has a resistance R, what is the resistance of wire B?
1. 4R 2. 2R 3. R 4. ½ R 5. ¼ R