CR Marchant MS
Grade 8 Science
Name: _________________________
DETERMINING FIELD OF VIEW
Lab Activity
PART A
1. With the 4X LOW POWER Objective lens in place over centre stage, put a plastic transparent ruler on the stage.
2. Focus on the millimetre marks of ruler using the coarse adjustment knob.
3. Move the ruler until one of the millimetre marks is at the edge of the FIELD OF VIEW.
4. Count the millimetres that span the FOV- this is your diameter for 4X.
5. Fill in your FOV diameter in mm in the table below.
6. Do the same procedure to measure the diameter of the FOV for the 10X MEDIUM POWER lens.
7. To calculate the FOV for 40X HIGH POWER you will use a different procedure.
Note below
Because HIGH POWER lenses provide a FOV less than 1mm, it cannot be measured with a ruler. To obtain a
measurement (diameter) you will have to calculate it mathematically using a ratio.
It is a 2 step process: Show Your Work Below
STEP 1 : Find the ratio between HIGH POWER – to – LOW POWER lenses
RATIO
=
STEP 2 : FOV ( HIGH POWER ) =
HIGH POWER LENS
LOW POWER LENS
=
ACTUAL LOW POWER FOV MEASURED
RATIO CALCULATED ( IN STEP 1 )
=
NOTE:
1 MM = 1000 Microns
OBJECTIVE LENS
STRENGTH
TOTAL MAGNIFICATION
POWER
( includes OCULAR LENS )
FIELD OF VIEW
( in millimetres )
UNITS
( in microns )
LOW POWER 4X
MEDIUM POWER 10X
HIGH POWER 40X
PART B
1. Place your “e” slide from your previous lab onto the stage for viewing
2. Estimate how many “e “ can fit across the FOV. Basically how many can you count if you put them side by side.
3. Calculate the width of the “e” using the formula below.
Width of “e” = FIELD OF VIEW WIDTH_____
Number of “e” that fit across
= ______________ This is the Width of my “e”