A doctor examines a mole with a 15.0 cm focal length magnifying glass held 12.4 cm from the mole.

a. What is its magnification?
b. Where is the image?
c. How big is the image of a 5.00 mm diameter mole?

Respuesta :

Answer:

a. Magnification = 6.1

b. The image formed is virtual, and on the same side of the lens as the object.

c. Image size = 119.8 squared millimetres

Explanation:

Magnification = [tex]\frac{Image distance}{Object distance}[/tex]

But, focal length, f = 15.0 cm, and object distance, u = 12.4 cm. Let the image distance be represented by v.

a. Applying the lens formula, we have;

[tex]\frac{1}{f}[/tex] = [tex]\frac{1}{u}[/tex] + [tex]\frac{1}{v}[/tex]

[tex]\frac{1}{15}[/tex] = [tex]\frac{1}{12.4}[/tex] + [tex]\frac{1}{v}[/tex]

[tex]\frac{1}{v}[/tex] = [tex]\frac{1}{15}[/tex] - [tex]\frac{1}{12.4}[/tex]

  = -[tex]\frac{13}{930}[/tex]

v = -75.1538

The image distance, v = -75.2 cm

Magnification = [tex]\frac{75.2}{12.4}[/tex]

                       = 6.0645

Magnification = 6.1

b. The image formed is virtual, and on the same side of the lens as the object.

c. Given that diameter of mole = 5.00 mm.

Its radius = [tex]\frac{diameter}{2}[/tex] = [tex]\frac{5.0}{2}[/tex]

              = 2.5 mm

Thus, the area of the mole would be;

A = [tex]\pi[/tex][tex]r^{2}[/tex]

   = [tex]\frac{22}{7}[/tex] x [tex](2.5)^{2}[/tex]

   = 19.643

A = 19.64 square millimetres.

Thus, the size of the image can be determined by;

Magnification = [tex]\frac{Image size}{Object size}[/tex]

Image size = Magnification x object size

                  = 6.1 x 19.64

                  = 119.804

The size of the image is 119.8 squared millimetres.

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