Which of the following statements is not true of the object known as Sgr A* in the center of our Galaxy?
A) It is by far the brightest source of visible light lying in the direction of the galactic center.
B) It is thought to harbor a black hole of about 4 million solar masses.
C) It is a source of x-ray emission that we have observed with telescopes in space.
D) It is a source of bright radio emission.
A) It is by far the brightest source of visible light lying in the direction of the galactic center.
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Answer the following statement(s) true (T) or false (F)
1. Consider the electric field shown below:
This is a physically possible static electric field (that is, we can calculate a well-defined potential difference between any two points in this field).
2. Consider the electric field shown below:
(This hypothetical field is uniform to the left of the boundary shown and zero to the right of that boundary.) This is a physically possible static electric field (that is, we can calculate a well-defined potential difference between any two points in this field)
Thin Films: A 360-nm thick oil film floats on the surface of a pool of water. The indices of refraction of the oil and the water are 1.50 and 1.33, respectively. When the surface of the oil is illuminated from above at normal incidence with white light, what is the wavelength of light between 400 nm to 800 nm wavelength that is most weakly reflected?
A. 520 nm B. 540 nm C. 560 nm D. 580 nm E. 600 nm
Which object produces a restoring force?
A. Rubber band B. All of these C. Spring D. Steel beam E. Leg bone
During each cycle of operation a refrigerator absorbs 45 cal from the freezer compartment and expels 85 cal to the room. If one cycle occurs every 8.0 s, how many minutes will it take to freeze 500 g of water, initially at 0°C? (Lv = 80 cal/g)
a. 800 min c. 120 min b. 4400 min d. 150 min