Which of the following statements about comets best describes the light we can observe?
A) A comet emits visible light and reflects infrared light.
B) A comet emits no light, but reflects visible light.
C) A comet emits visible light and infrared light.
D) A comet emits infrared light and reflects visible light.
D
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Thin Lenses: Starting from very far away, an object is moved closer and closer to a converging lens, eventually reaching the lens. What happens to its image formed by that lens? (There could be more than one correct choice.)
A. The image gets closer and closer to the lens. B. The image gets farther and farther from the lens. C. The image eventually changes from virtual to real. D. The image eventually changes from real to virtual. E. The image keeps getting larger and larger.
A lamp radiates 75. J/s when the room is set on 27°C but it radiates 90. J/s when the room temperature drops to 10.°C. What is the temperature of the lamp?
A) 86.°C B) 97.°C C) 86. K D) 110.°C E) 97. K
Instructions: On occasion, the notation 
will be a shorthand notation for 
.
If vector 
is added to vector 
, the result is 
. If is subtracted from 
, the result is 
. What is the magnitude of ?
A. 5.1
B. 4.1
C. 5.4
D. 5.8
E. 8.2
An electron has the same de Broglie wavelength as the wavelength of a 1.8 eV photon
What is the speed of the electron? (melectron = 9.11 × 10-31 kg, c = 3.00 × 108 m/s, 1 eV = 1.60 × 10-19 J) A) 840 m/s B) 910 m/s C) 980 m/s D) 770 m/s E) 1100 m/s