You have a choice between two lenses of focal lengths f_a and f_b,where f_b = 2f_a,to use as the objective lens in building a compound microscope.If the magnification you obtain using lens a is M_a,what will be the magnification when using lens b? A)M_b = 2 M_a B)M_b = 4 M_a C)M_b = 8 M_a D)M_b = M_a/4 E)M_b = M_a/2

Question

Quizplus · Accepted Answer

The magnification of a compound microscope using an objective lens and an eyepiece lens is given by: M = M_obj * M_eyepiece where M_obj is the magnification of the objective lens and M_eyepiece is the magnification of the eyepiece lens. Since the objective lenses have different focal lengths but the same eyepiece lens is used, we can write: M_a = f_eyepiece / f_a M_b = f_eyepiece / f_b = f_eyepiece / 2f_a Dividing these two equations, we get: M_b / M_a = (f_eyepiece / 2f_a) / (f_eyepiece / f_a) = 1/2 or M_b = (1/2)M_a Therefore, the magnification when using lens b is half of the magnification when using lens a, which gives us the answer: Choice E: M_b = M_a/2

You Have a Choice Between Two Lenses of Focal Lengths