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Reading glasses of what power are needed for a person whose near point is 125 cm , so that he can read a computer screen at 54 cm ? Assume a lens-eye distance of 2.0 cm .

Respuesta :

Answer:

1.11 dioptre

Explanation:

[tex]d_{i}[/tex] = Distance of the image = - (125 - 2) = - 123 cm

[tex]d_{o}[/tex] = Distance of the object = 54 - 2 = 52 cm

[tex]f[/tex] = Focal length of the lens

Using the equation

[tex]\frac{1}{d_{o}} + \frac{1}{d_{i}} = \frac{1}{f}[/tex]

[tex]\frac{1}{52} + \frac{- 1}{123} = \frac{1}{f}[/tex]

[tex]f = 90.1 [/tex] cm

Power of the lens is given as

[tex]P = \frac{100}{f}[/tex]

[tex]P = \frac{100}{90.1}[/tex]

[tex]P = 1.11[/tex] Dioptre

onyebuchinnaji

The power of the lens is 1.11 D.

Focal length of the reading glass

The focal length of the reading glass is calculated as follows;

  • Image distance = -(125 - 2) = -123 cm
  • object distance = 54 cm - 2 cm = 52 cm

[tex]\frac{1}{f} = \frac{1}{u} + \frac{1}{v} \\\\\frac{1}{f} = \frac{1}{52} - \frac{1}{123} \\\\\frac{1}{f} = 0.0111\\\\f = 90.1 \ cm = 0.901 \ m[/tex]

Power of the lens

The power of the lens is the inverse of the focal length of the lens measured in meters.

P = 1/f

P = 1.11 D

Learn more about power of lens here: https://brainly.com/question/17166887

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