In this lesson, we’ll explore what magnification means as well as some of the many tools that enable you to magnify small objects. We’ll also consider how to calculate the total magnification of an object and how its magnified size relates to its actual size.
Definition of Magnification
Magnification refers to the act of visually enlarging an object, meaning that the object itself doesn’t become physically larger but only larger in appearance. This notion of magnification can arise in either of two forms: microscopic magnification is what we use when we make small objects appear larger, while telescopic magnification makes distant objects appear closer (and thus clearer and more defined).It’s important to note that these forms both utilize very different tools and formulas; therefore, to avoid any confusion between the two, herein we will specifically focus on microscopic magnification and the types, formulas, and calculations pertaining to that process alone.
We’ll save telescopic for its own lesson.
The term simple lens refers not to the ease of using these lenses but to the number of lenses that the tool itself has. Magnifying glasses, like the one you might see Sherlock Holmes use while he’s tracking down clues or your grandparents using while reading the newspaper, are simple lenses; they use only one lens to magnify the image in front of it. Magnifying glasses are the lowest power (strength) magnification tools you could use as they range from 2x-6x, meaning that they can only magnify an object so that appears two times larger than it really is while some can magnify an object up to six times larger.Coddington hand tools, first developed in the 1700’s, are another variety of simple lens that can offer the user up to 15x magnification. It is capable of reaching a higher magnification than a magnifying glass due to the thickness of the lens along with the deep central groove cut into the glass. Unfortunately, the central grove reduces the amount of area that can actually be seen at any given time.
While a simple lens uses only one magnifying element, compound lenses use two or more lenses to increase the microscopic magnification of an object. Now you might automatically think of a microscope and, while you wouldn’t be wrong, they aren’t the only compound tools.Think back to the last time you saw a movie where a jeweler or a robber assessed the quality of a diamond or a gem. To see any flaws in the gems they needed a powerful magnifying device, called a loupe, that can reach up to 10x magnification. Loupes meant for one eye are known as a monocular loupe however you’re probably more familiar with the lower magnification binocular pair that your dentist donned the last time you got an oral exam.
Calculating Compound Lens Magnification
Okay, so let’s take a minute to discuss calculating magnification. This would be most readily relevant to any sort of biology laboratory work that you do which uses a microscope to magnify cells or microscopic organisms.
If you’ve ever used a microscope you’ll remember that it has a pair of ocular lenses as well as a second set of lenses, called objective lenses. These two pair of lenses together define this instrument as a compound tool.Now, as you might imagine, we have to address all sets of lenses in our calculation so we can discern the total magnification, or the complete magnification that you are viewing the object at. The ocular lenses carry a magnification of 10x (meaning they, alone, magnify the object ten times larger than it really is).
The objective lenses, on the other hand, vary in magnification from a 4x scanning lens to a 10x, 40x, or even 100x oil immersion lens. The formula for calculating microscopic magnification is simply the ocular lens magnification times the objective lens magnification. In other words, the total magnification of using the 4x scanning lens is (10x) * (4x) = 40x.With that said, a compound microscope is capable of a total magnification ranging from forty times the normal size of the sample to up to 1,000 times ((10x) * (100x)) its normal size.
Magnification refers to the act of visually enlarging an object, microscopic magnification is when a small object is made larger, while telescopic magnification makes distant objects appear closer. Simple lenses, like a magnifying glass or a Coddington lens, use a single lens to magnify the image in front of it, while compound lenses, such as a jeweler’s loupe or a microscope, use two or more lenses to increase the magnification of an object. The total magnification of a compound lens is the complete magnification that you are viewing the object at and is calculated by multiplying the magnification of the lenses together.
In the compound microscope, total magnification is the ocular lens magnification multiplied by the objective lens magnification.