Question

A 5-inch, f/10 telescope has a 2-inch eyepiece focal. Its magnifying power is: (PLEASE HELP)

A.10X
B.25X
C.50X
D.100X

Answer 1

D. 100x..............

Answer 2

B.25x

Explanation:

given data

diameter = 5-inch

f/ratio = f/10

eyepiece focal = 2-inch

solution

we know that f/ratio measures the light gathering power of a lens.

so that it is expressed as focal length of the lens divided by  diameter

f/ratio = $\frac{focal\ length}{diameter}$      ......................1

put here value and we get

focal length = 10 × 5 = 50 inches

and Magnification power is express as

Magnification power M =      .......................2

put here value and we get

Magnification power M = $\frac{50}{2}$

Magnification power M = 25 x

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