To make a compound microscope you can add a 2nd lens to the simple magnifier arrangement. The magnification produced by the objective lens (m) is multiplied by the magnification of the simple magnifier (Me), so the total magnifying power (MP) is increased. That is: MP = m Me.Calculate how far away from the objective lens you need to place the object to be viewed to produce a magnifcation of m = - 20, if the focal length of the lens is fo = 10.5 cm. Give answer to 3 significant figures.
Question
To make a compound microscope you can add a 2nd lens to the simple magnifier arrangement. The magnification produced by the objective lens (m) is multiplied by the magnification of the simple magnifier (Me), so the total magnifying power (MP) is increased. That is: MP = m Me.Calculate how far away from the objective lens you need to place the object to be viewed to produce a magnifcation of m = - 20, if the focal length of the lens is fo = 10.5 cm. Give answer to 3 significant figures.
Solution
The magnification (m) of a lens is given by the equation m = -d_i / d_o, where d_i is the image distance and d_o is the object distance.
In this case, we know that m = -20 and we want to find d_o.
We also know that the lens equation is 1/f = 1/d_o + 1/d_i, where f is the focal length of the lens.
We can rearrange this equation to find d_i = 1/(1/f - 1/d_o).
Substituting the given value of f = 10.5 cm into this equation gives d_i = 1/(1/10.5 - 1/d_o).
We can then substitute this value of d_i into the magnification equation to find d_o.
This gives -20 = -1/(1/10.5 - 1/d_o) / d_o.
Solving this equation for d_o gives d_o = 10.5 cm / 21 = 0.5 cm.
Therefore, the object needs to be placed 0.5 cm away from the objective lens to produce a magnification of -20. This answer is already to 3 significant figures.
Similar Questions
For a compound microscope the magnifying power (MP) is the objective magnification (m) multiplied by the eyepiece magnification (Me). Generally two small focal length lenses are used with around the same value of f. A simple magnifier has been set up with a virtual image produced at 25 cm away from the lens of focal length fe. The object is placed at the required distance 6.3 cm away and can be viewed. Another lens is now added as the objective in a compound microscope. The first lens is the eyepiece. The objective lens has focal length of fo = 9.5 cm and for a magnification of m = -2 it can be calculated that the object now needs to be placed 14.25 cm away from this lens. How far apart must the two lenses be set to construct a compound microscope with the virtual image produced at 25 cm?Give your answer to 4 significant figures.
In a compound microscope, the focal length of objective lens is 1.2 cm and focal length of eye piece is 3.0 cm. When object is kept at 1.25 cm in front of objective, final image is formed at infinity. Magnifying power of the compound microscope should be:
Magnification of a compound microscope does not depend upon:
A simple magnifier is made using a single convex lens by placing the object closer than the focal point. To maximise the magnification the object is placed so the image is formed at the near point. By convention this is taken to be 0.25 m from the lens.For a lens with focal length f = 0.08 m, calculate the magnification produced. (You will first need to calculate the object distance, o, required to produce a virtual image at the near point i= -0.25 m.)Express answer to two decimal places.
Find the magnifying power of a compound microscope whose objective and eyepiece are of focal lengths 4.0 cm and 6.0 cm respectively and the object is placed 5.0 cm beyond the objective. Assume that the final image is formed at the least distance of distinct vision (25 cm)
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