Calculate the linear magnification of an image Three metric units that will be useful for this and all future microscope activities are the millimeter (mm) and micrometer (μm) and nanometer (nm) (*The micro symbol ‘μ’ looks like a ‘u’ with a longer tail in the front) 1 meter (m) = 1000 millimeters (mm) 1 millimeter (mm) = 1000 micrometers (μm) 1 micrometer (μm) =1000 nanometers(nm) m= 100 or 1m mm= 10-3 or 0.001m μm = 10-6 or 0.000001m Let’s read the Magnification in Biology Sheet

Before we begin: Note: Numbers written like this: 1.26 x 105 mean you move the decimal point to the right. In this case you move it 5 times: 1.26 x 105 = 126000.0 1.2 6 0 0 0 0 .

magnification is 40,000 then: The actual size of an object can be calculated using the same formula: Magnification = Image size Actual size of object MIA Therefore: Actual Size of object = Image size Magnification AIM If an image is measured and found to have a length of 6 mm (6,000 mm) and the magnification is 40,000 then: Actual size of object = 6,000 40,000 = 0.15 mm

Let’s look at the worked examples: Worked example 1: Calculation of the magnification of a drawing Worked example 2: Calculation of magnification and conversion of units Worked example 3: Calculating magnification from a scale bar When we are happy with this you will move onto some individual tasks

Task: 10 minutes Read the calculating linear magnification sheet and go through worked example again THEN Complete the calculating linear magnification sheet 8 marks Cell Magnification practice 10 marks 2 x 2 mark exam questions 1x 8 mark exam question ARE WE HAPPY NOW???

Plenary: Complete the examination question 10 marks =10 minutes