Advertisements
Advertisements
Question
The near point and the far point for a person are 50 cm and 500 cm, respectively. Calculate the power of the lens the person should wear to read a book held in hand at 25 cm. What maximum distance is clearly visible for the person with this lens on the eye?
Advertisements
Solution
Case (i)-
p = `1/"f"`
`1/"f" = 1/"v" - 1/"u"`
u = - 25 cm
v = 50 cm
p = `- 1/50 - 1/(-25)`
p `= - 1/50 + 1/25`
p = `1/50` cm
p = `1/0.5`
p = 2D
Case (ii-
v = - 500 cm, u = ?,
p = `1/"f" = 2`
f = `1/2`
f = 0.5
f = 50 cm
`1/"f" = 1/"v" - 1/"u"`
`1/50 = - 1/(-500) + 1/"u"`
`1/"u" = 1/500 + 1/50`
`1/"u" = (1 + 10)/(500) = 11/500`
u = `500/11`
u = 45.45 cm
APPEARS IN
RELATED QUESTIONS
Answer the following question in detail.
Define and describe the magnifying power of an optical instrument.
Answer the following question in detail.
How does magnifying power differ from linear or lateral magnification?
Answer the following question in detail.
What is the limitation in increasing the magnifying powers of a simple microscope?
Answer the following question in detail.
What is the limitation in increasing the magnifying powers of the astronomical telescope?
Discuss about simple microscope and obtain the equations for magnification for near point focusing and normal focusing.
What are the uses of spectrometer?
What is myopia?
What is astigmatism? What is its remedy?
Obtain the equation for resolving the power of the microscope.
Mention different parts of the spectrometer.
Explain the preliminary adjustments of the spectrometer.
Explain the experimental determination of the material of the prism using a spectrometer.
A compound microscope has a magnifying power of 100 when the image is formed at infinity. The objective has a focal length of 0.5 cm and the tube length is 6.5 cm. What is the focal length of the eyepiece.
A light wave of wavelength λ is incident on a slit of width d. The resulting diffraction pattern is observed on a screen at a distance D. If linear width of the principal maxima is equal to the width of the slit, then the distance D is
When a convex lens of 12.5 cm focal length is used as a magnifying glass, normal eye can see an object clearly at a distance of 25 cm. The magnifying power of the instrument is ____________.
If astronomical telescope of length 1.53 m has magnifying power of magnitude 50, the values of fo and fe are ____________.
The magnifying power of a telescope is nine. When it is adjusted for parallel rays, the distance between the objective and eyepiece is 20 cm. The focal length of objective and eyepiece are respectively.
The magnifying power of a telescope is high if its objective and eyepiece have respectively ______.
A camera objective has an aperture diameter of d. If the aperture is reduced to diameter d/2, the exposure time under identical conditions of light should be made ______.
