Video Transcript
The table shows the magnification
of lenses in five different microscopes. Choose the microscope that gives
the highest total magnification. (A) 10 times, 20 times. (B) Five times, 50 times. (C) 10 times, 10 times. (D) Five times, 10 times. Or (E) 10 times, four times.
To answer this question correctly,
let’s first review some key facts about the use of microscopes to magnify
objects. First of all, what is
magnification? Magnification is the process by
which an object is made larger in appearance, and this can be done by using
magnifying lenses. Microscopes can be used to magnify
specimens that we cannot see with a naked eye, such as microorganisms and cells. Microscopes work using magnifying
lenses. A lens is a piece of glass or other
transparent material with curved sides that bends the light rays to form an image of
an object.
There are usually two lenses used
in the common light microscope shown here: the objective lens, which is nearest the
object, and the eyepiece lens, which is the lens the observer looks through. So let’s see how we get a magnified
image of an object. The object we want to look at is
placed on a glass slide, which is then put onto the stage. Light is shone through the object
on the slide from a source below. The light passes from the object
through the objective lens, then through the eyepiece lens into your eye. As the light passes through the
solid objective lens, it bends, forming a magnified image. The light then bends again as it
passes through the eyepiece lens, which further magnifies the image.
The magnification of each lens is
marked on the side of it. The common school microscope has
three or four objective lenses, usually four times, 10 times, 40 times, and 100
times. The eyepiece lens is usually of 10
times magnification. The total magnification of the
object is calculated by multiplying the magnification of the eyepiece lens by the
magnification of the objective lens being used. So if you were using the lowest
power objective lens, the magnification would be 10 times four, which equals 40
times. If using the highest power
objective lens, it would be 10 times 100, which equals 1000 times.
Now that we have looked at the
magnification power of microscopes, we can return to the question. Let’s work out the magnification of
each option to come up with the correct answer. The total magnification of option
(A) is 10 times 20, which equals 200. The total magnification of option
(B) is five times 50, which is 250. The total magnification of option
(C) is 10 times 10, which is 100. For option (D), it is five times
10, which is 50. And for (E), it is 10 times four,
which is 40. The highest total magnification out
of these choices is 250 times.
So the correct answer to the
question is (B). The microscope that gives the
highest total magnification has an eyepiece lens of five times and an objective lens
of 50 times.
