Magnification

Magnification

Thursday 21st January 2021

Open Ended

Why do we use kilometers (km) instead of milimeters (mm) when measuring the distances between cities?

Converting Units

• When converting from a smaller unit to larger we / 1000. For example, if we had 100 um, this is the same as saying that we have 0.1 mm.

• But if we go from a larger unit to a lower unit we x 1000. So for example, if we had 1 mm, this is the same as 1000 um.

Multiple Choice

What is 200 um in nm?

• 0.2

• 2

• 2000

• 200'000

Multiple Choice

What is 5000 nm in um?

• 500'000

• 5

• 50

• 0.5

Multiple Choice

What is 4 mm in nm?

• 4'000

• 4'000'000

• 40'000'000

• 400

IAM Equation

• Image size = actual size x magnification

• actual size = image size / magnification

• magnification = image size / actual size

If an object has an image size of 2mm and we are using magnification of x1500,what is the actual size?

As we are looking for the actual size, we use A = I / M.

I = 2 mm

M = x1500

A = 2 / 1500

A = 0.001333...

If the image you observe down a microscope is 6 mm, and the actual size is 3 um, what is the magnification?

I = 6 mm; A = 3um

But first we need to convert 6 mm to um!

6 x 1000 = 6000um

Then to find M we use M = I / A.

M = 6000 / 3

M = x2000

Multiple Choice

If we were to look at a bacterial cell down a microscope and observe an image size of 2.5 mm, and we are using a magnification of x400, what is the actual size of the bacteria?

• 100

• 1000

• 0.00625

• 0.05

Multiple Choice

If we were to look at a bacterial cell down a microscope and observe an image size of 100um, and we are using a magnification of x1000, what is the actual size of the bacteria in nm?

• 0.1

• 10

• 100

• 1000