Question

A microorganism viewed under microscope with $40\times$ objective and $10\times$ eye piece measures $4000\mu$m. The same microorganism observed under dissection microscope with $10\times$ lens would measure

• A. $40\mu$m
• B. $100\mu$m
• C. $10\mu$m
• D. $400\mu$m

Answer 1

Answer: (B)

$100\mu$m

As we knew, dissection microscopes have less magnification than a compound microscope. Compared to compound microscopes which have several lenses, dissection microscopes only have one set of lenses. 10X magnification is the most common in dissecting microscopes. To calculate total magnification how much your image to your specimen is being magnified (on) increased, you should multiply eyepiece magnification by the objective lens magnification. Here, the eyepiece magnification is 10X and the objective magnification is 40X the total magnification will be 400X.
magnification = size of the image/size of specimen
=> 400X = 4000μm/size of specimen
=> size of specimen = 4000/400 = 10μm
Now, we have the size of the specimen that is 10 μm. By using this we calculate the size of the image in the dissection microscope.
By using the same formula of magnification,
Here 10X is the total magnification of the dissecting microscope.
=> 10X = size of image/10μm
Therefore, size of image = 10*10 = 100μm
So, the correct option is B.