The distance from the center of the lens to its principal focus is called the:
A. scaling factor
B. magnification
C. secondary focus
D. focal length

Did you know that a single bee would have to go to over 2 million flowers to make a single pound of honey?

In 2001, records showed that local stocks of fish were down worldwide. yet, records of harvests indicated that fish were being taken at records rates. what was actually happening?

Which of the following types of stars is most likely to end up as a supernova? in graph a, the curve peaks at 800 nm, in the red section of the visible light spectrum. in graph b, the curve peaks at 550 nm, in the green section of the visible light spectrum. in graph c, the curve peaks at 450 nm, in the blue section of the visible light spectrum. in graph d, the curve peaks at 300 nm, in the violet section of the visible light spectrum. a b c d