Understanding Cell Structure: Basics of Microscopy and Magnification

diving right into it we are going into chapter one right now and chapter one is all about

cell structure now before we talk about cell structure we are gonna have to talk a little bit

about something called cell microscopy the word microscopy just basically

implies that we are going to be using an apparatus called the microscope all right when we are talking about a

microscope okay so what's the purpose of a microscope we kind of know that the

school has a microscope called the light microscope and the microscope's

main function is just basically to magnify a specimen to magnify a specimen

size and when we are talking about the specimen size okay it's not the actual specimen

size by the way we are not it's not like a a weird uh sci-fi ray gun to kind of enlarge the

size of the actual specimen however it is to magnify or the key word here is basically magnification we have to

understand what the word magnification is and magnification is basically to enlarge the image size

of a specimen right so in our eyes if we are looking at a particular specimen and let's say that's

the actual size of a specimen that red dot okay the actual size over there uh

what happens is when we look at it okay our brain will basically register a slightly bigger size okay

basically so this is what's supposed to happen over here and in this case what we register is the

image size but how does this happen how does this size

over here become this one over here that process okay in between is called magnification and for magnification to

happen uh you can either use a light microscope or you can use an electron microscope so

let's keep it very simple let's talk about the light microscope first okay

so for the light microscope i'm not gonna do the exact uh structure of the light microscope i

mean that's not so important what we have to know is we have to kind of understand the fundamentals

first the fundamentals are as follows when i say fundamentals i mean the basics we kind of have to know

how a microscope works imagine if you just have an object over here

this is just basically the specimen be it a cell whatever you're looking at it under the

microscope if you want to be able to look at a specimen you have to understand

how are we able to see something if this is our eye you are only able to see something

if light was to hit the specimen so that's light over that light is able to hit the specimen and

the specimen must be able to reflect the light into your eyes then your photoreceptors in your eye detect the

light it sends an impulse to your brain and your brain goes

i'm able to see the specimen basically that's what's supposed to happen but let's talk about

what if the light was um let's say the object is like a transparent object if it's a transparent

object the light will just basically pass through and in that kind of situation the light

will not be reflected and we will not be able to see anything at all

that's what's supposed to happen so the first fundamental thing that you have to understand

is if you want to be able to see something if you want to be able to see something

the specimen interrupts the light and reflects the light

into our eyes that's the first thing we must understand so only when the light hits the specimen

and the light is reflected into our eyes we are able to see it fine now what's the big deal where does

magnification come in magnification comes in when you kind of put a lens

over here now when you put a lens over here what actually happens is it will go through the lens and in this

situation over here when it enters our eyes our eyes will comprehend the specimen to

be larger than it actually is this over here is the process of

magnification so this is the actual size of the specimen over here and this is the image size

pretty simple fine now and if we were to look at the actual size

over here if we were to make it bigger and this is the image size over here

this is just the act of magnifying it okay magnification equals you multiply the actual size and you'll

actually get the image size over here so that's how they get the formula

the formula equals to actual times magnification equals to image or you can also just rearrange it

where you can put magnification equals to image over actual that's how the formula comes to be so

let's try a basic example basic example is as such if you have an actual size of a cell

which is about for example 10 micrometer and based on the

magnification of the cell we are certain the diameter of the cell was when we

looked at it under the microscope it was 10 millimeters so in this case they asked

you to calculate for example in the exam what is the magnification basically magnification okay i'm just writing it

like that so magnification equals to image over actual

and magnification equals to 10 millimeters which is the one that you are looking at

under the microscope okay what you're looking at what you see and 10 micrometer

is the actual size now a lot of students not a lot of students okay that's that's a bit of an unfair

statement to make but a few students have a tendency to just divide 10 millimeters to 10 micrometers

and they'll get the answer one and that is so wrong okay in maths the units for the numerator and the

denominator they have to be similar so you'll have to convert millimeter to micrometer and

to convert millimeter to micrometer you can just basically multiply it by a thousand

right and in this case it will be 10 000 micrometers divided by 10 micrometers and the answer in this case will be a

thousand that is the magnification right here okay

it's quite straightforward and of course the basic units that you'll have to know the units

in magnification uh rarely do we use centimeters but on the off chance it might come out

we have millimeters we have micrometer i'm not best at writing micrometer over there

okay and we also have a new one in igcse you only had to learn these three scales but you also have to introduce a

new one nanometer because we're going to be talking about organelles and organelles some

organelles fall under the scale of nanometers okay conversion of centimeters to millimeters

is multiplied by 10 millimeters to micrometers multiplied by a thousand

some books will put it as 10 to the power of three this to this micrometer to nanometer again multiply

10 to the power power of three or a thousand and nanometer to micrometer

it's the opposite you just divide it then divide the thousand divide a thousand over here that's a

comma by the way that's not a decimal place it has a separator all right and this one is divided by 10.

okay so these are the units that you'll have to know and you'll have to be able to

convert the units effortlessly in the exam all right they give you like for example three

millimeters okay three millimeters and they ask you to convert it into let's say micrometer so micrometer in

this case will be three millimeters times a thousand and therefore

it is equivalent to 3 000 micrometers some students do ask do i have to put the separator in the exam no you don't

have to it's just a habit um if you just basically want to adjust 3000 micrometer

go ahead no problems with that and if they do ask you to convert it into nanometer

then what you'll have to do is you'll have to do three multiplied by a thousand

multiply by another thousand and in this case it will be 3 million nanometers so

the conversion is something that we must be well versed with that is just basically what

magnification is all about magnification is just taking the actual specimen this is the

actual specimen and we magnify it using the lenses in the microscope so that when we

view it under the microscope what we are looking at is an enlarged image of the specimen

that is just what magnification is all about pretty simple and pretty straight

forward and the most important thing to also take away from this is if you want to be able to see

something if you want to be able to see something it must have the capability of interrupting the light

and reflecting the light this will be important for later and once it interrupts and reflects the

light it will then enter our eyes and therefore we are able to

comprehend the image that's how we look at it that's how we look at things on a daily

basis so for the next video what we're going to be looking at is

we're going to be seeing the wavelengths of a light microscope