Magnification and SizeMagnification and Size

Measuring biological specimens using millimetres as units

Measuring biological specimens using millimetres as units

To accurately measure the size of cellular structures we need a suitable scale:

To accurately measure the size of cellular structures we need a suitable scale:

Ideally, we need a scale we can see directly alongside the cells we are

observing:

Ideally, we need a scale we can see directly alongside the cells we are

observing:

Start by putting a ruler under the microscope:

Start by putting a ruler under the microscope:

Appearance of ruler at medium magnification

Appearance of ruler at medium magnification

Appearance of tissue at medium magnification

Appearance of tissue at medium magnification

Estimating cell size at medium magnification

Estimating cell size at medium magnification

1 mm

1 mm

12

5

1mm / 12 cells = 0.083 mm

1mm / 5cells=

0.2 mm

Other unitsOther units

Mean width of cells = 0.083 x 1000 = 83µm

Mean length of cells = 0.2 x 1000 = 200µm

Diameter of field of

view/mm

No. of cells

lengthways

No. of cells

widthways

Mean length (mm)

Mean width (mm)

1.00 5 12 0.2 0.083

1mm = 1000µm

Calculating actual size:Calculating actual size:

Calculating magnification & actual size:Calculating magnification & actual size:

Calculating actual size:Calculating actual size:

Calculating magnification:Calculating magnification:

Calculating magnification & actual size:Calculating magnification & actual size:

Calculating actual size:Calculating actual size:

Cell MagnificationCell Magnification

This diagram shows the general structure of an animal cell from an electron microscope.

Calculate the magnification factor.

Calculate the length of G - a mitochondrion.

Calculate the diameter of the nucleus.

Calculate the width of the cell at its widest part.

____ 0.005 mm

Plant cell magnificationPlant cell magnification

____ 0.040 mm

Diagram shows the generalised structure of a plant cell as seen with an electron microscope.

Calculate the magnification factor.

Calculate the width of the cell.

Calculate the length of the vacuole.

Magnification of an Illustration = Size of Illustration / Actual Size

For example, a magnification of 1x means the illustration is the same size as the object, 100x means the illustration is 100 times bigger than the object, etc. It is important that you first calculate or measure the actual size of an object, and from that calculate the magnification of the illustration .

Always draw the magic triangle and fill in the information you have.

Always check your units.

Magnification of an Illustration = Size of Illustration / Actual Size

For example, a magnification of 1x means the illustration is the same size as the object, 100x means the illustration is 100 times bigger than the object, etc. It is important that you first calculate or measure the actual size of an object, and from that calculate the magnification of the illustration .

Always draw the magic triangle and fill in the information you have.

Always check your units.

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