A camera has a converging lens with a focal length of 56 mm. If the f-number is 2.8, what is the diameter of the lens (in mm)?
a. 10
b. 31
c. 0.50
d. 20
e. 50
d
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What is Jupiter's Great Red Spot?
A) a giant storm that is about twice as wide as the planet Earth B) a giant crater on the surface of Jupiter C) a portion of strongly heated gas near the surface of Jupiter caused by a collision with a comet D) a huge patch of sulfur in Jupiter's atmosphere E) reflected sunlight that is red for the same reason sunrises and sunsets are red on Earth
Three point charges, 
and
are located at the vertices of an equilateral triangle. If 
what value must q3 have so that the total potential energy of the arrangement is zero?
A. q1 B. 0.5 q1 C. -0.5 q1 D. (q1+ q2)/2 E. no value will have this result
Velocity: If you are driving 72 km/h along a straight road and you look to the side for 4.0 s, how far do you travel during this inattentive period?
A. 18 m B. 20 m C. 40 m D. 80 m
Thin Lenses: An object is placed 15 cm to the left of a double-convex lens of focal length 20 cm. Where is the image of this object located?
A. 60 cm to the right of the lens B. 60 cm to the left of the lens C. 8.6 cm to the right of the lens D. 8.6 cm to the left of the lens E. 30 cm to the left of the lens