1) A microscope has a 9.0 eyepiece and a 63.0 objective 20.0 cm apart. (a) Calcu

Question

1) A microscope has a 9.0 eyepiece and a 63.0 objective 20.0 cm apart.

(a) Calculate the total magnification. 567 Correct

(b) Calculate the focal length of each lens.

:. eyepiece 2.78cm Correct

:. objective 2.10cm Incorrect

(c) Calculate where the object must be for a normal relaxed eye to see it in focus. (cm)

2) Two stars 13 light-years away are barely resolved by a 73 cm (mirror diameter) telescope. How far apart are the stars? Assume = 550 nm and that the resolution is limited by diffraction. (m)

3) A small insect is placed 5.32 cm from a +6.13 cm focal-length lens. (Use the correct sign conventions)

(a) Calculate the position of the image. (in cm from the lens)

Explanation / Answer

2)

d = diameter = 73 cm = 0.73 m

= wavelength = 550 x 10-9 m

D = distance between the stars = 13 light yr = 13 x 9.46 x 1015 m

separation of stars is given as

S = 1.22 D ( /d)

inserting the above values

S = 1.22 (13 x 9.46 x 1015 ) (550 x 10-9 / 0.73)

S = 1.13 x 1011 m

3

a)

do = object distance = 5.32 cm

f = focal length = 6.13 cm

Using the lens equation

1/di + 1/do = 1/f

1/di + 1/5.32 = 1/6.13

di = - 40.3 cm

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