Angular Magnification

Q. You are given two converging lenses of focal lengths 1.25 cm and 5 cm to design a compound microscope. If it is desired to have a magnification of -30, find out the separation between the objective and the eyepiece.

Q. The length of the compound microscope is $20\text{cm}$. The focal length of the eyepiece is $5\text{cm}$. If the magnifying power for the relaxed eye is $25$, then find the object distance from the objective lens.

1. $6\text{cm}$
2. $5\text{cm}$
3. $4\text{cm}$
4. $3\text{cm}$

Q. In a compound microscope, magnification will be large, if the focal length of the eye piece is

1. Large
2. Smaller
3. Equal to that of objective
4. Less than that of objective

Q.

A simple microscope is rated 5 X for a normal relaxed eye. What will be its magnifying power for a relaxed farsighted eye whose near point is 40 cm?

Q.

For an object at infinity, the focal length of a normal eye-lens is about

Q. A thin glass (refractive index 1.5) lens has optical power of – 5D in air. Its optical power in a liquid medium is

1. $\frac{5}{8}D$
2. - 25D
3. 25 D
4. -1D

Q.

For which of the following colour, the magnifying power of a microscope will be maximum

1. White colour

2. Red colour

3. Violet colour

4. Yellow colour

Q. What should be the distance between the object in Exercise 9.30 and the magnifying glass if the virtual image of each square in thefigure is to have an area of 6.25 mm2 . Would you be able to see thesquares distinctly with your eyes very close to the magnifier ?[Note: Exercises 9.29 to 9.31 will help you clearly understand thedifference between magnification in absolute size and the angularmagnification (or magnifying power) of an instrument.]

Q. The length of the compound microscope is $18\text{cm}$. The magnifying power for the relaxed eye is $28$, find the object distance from the objective lens, if the focal length of the eyepiece is $4\text{cm}$.

1. $3.125\text{cm}$
2. $3.750\text{cm}$
3. $2.125\text{cm}$
4. $2.750\text{cm}$

Q. A thin glass (refractive index 1.5) lens has optical power of – 5D in air. Its optical power in a liquid medium is

1. $\frac{5}{8}D$
2. - 25D
3. 25 D
4. -1D

Q. A simple microscope is rated $\text{5X}$ for a normal and relaxed eye. What will be its magnifying power for a relaxed eye, whose near point is $50\text{cm}$?

1. $\text{8X}$
2. $\text{4X}$
3. $\text{10X}$
4. $\text{20X}$

Q. The length of the compound microscope is $18\text{cm}$. If the magnifying power for the relaxed eye is 28, find the object distance for the objective lens. Focal length of the eyepiece is $4\text{cm}$ and $D=25\text{cm}$.

1. $3.12\text{cm}$
2. $3.75\text{cm}$
3. $2.50\text{cm}$
4. $2.75\text{cm}$

Q. A student sitting on the last bench can read the letters written on the blackboard but is not able to read the letters written in his text book. Which of the following statements is correct?

1. The near point of his eyes has receded away.
2. The near point of his eyes has come closer to him.
3. The far point of his eyes has come closer to him.
4. The far point of his eyes has receded away.

Q. The diameter of the eye ball of a normal eye is about $2.5cm$. The power of the eye lens varies from

1. $9D$ to $8D$
2. $44D$ to $40D$
3. None of these
4. $40D$ to $32D$

Q. Telescope has an objective of focal length 50 cm and an eye-piece of focal length 5 cm. The least distance of distinct vision is 25 cm. The telescope is focused for distinct vision on a scale 2 m away from the objective. Magnification produced is

1. 2
2. 1
3. 3
4. 4

Q. A lens made up of different material forms two images of a point object ${}^{\prime }{O}^{\prime }$ as shown in figure. Then

1. ${\mu }_1>{\mu }_2$
2. ${\mu }_1={\mu }_2$
3. ${\mu }_2>{\mu }_3$
4. Data imufficient

Q. If the focal length of the objective lens is increased, then the magnifying power of -

1. compound microscope will increase, but that of telescope will decrease.
2. both compound microscope and telescope will increase.
3. both compound microscope and telescope will decrease.
4. compound microscope will decrease, but that of telescope will increase.

Q.

For which of the following colour, the magnifying power of a microscope will be maximum

1. White colour

2. Red colour

3. Violet colour

4. Yellow colour

Q. A thin glass (refractive index 1.5) lens has optical power of – 5D in air. Its optical power in a liquid medium is

1. $\frac{5}{8}D$
2. - 25D
3. 25 D
4. -1D

Q. Your friend is having eye sight problem. She is not able to see clearly a distant uniform window mesh and it appears to her as non-uniform and distorted. The doctor diagnosed the problem as:

1. Myopia and hypermetropia
2. Astigmatism
3. Myopia with astigmatism
4. Presbyopia with astigmatism

Q. Which of the following statements are true in the context of a compound Microscope?
(A) Each lens produces a virtual and inverted image
(B) The objective has a very short focal length
(C) The eyepiece is used as a simple magnifying glass
(D) The objective and eyepiece are convex and concave lenses respectively

1. (A), (B) and (D)
2. (B) and (C)
3. (B) and (D)
4. (A), (C) and (D)

Q. The size of an object as perceived by an eye depends primarily on,

$\left(i\right)$ Actual size of the object

$\left(ii\right)$ Distance of the object from the eye

$\left(iii\right)$ Aperture of the pupil

1. $\left(i\right)$ and $\left(ii\right)$
2. $\left(i\right)$ and $\left(iii\right)$
3. $\left(ii\right)$ and $\left(iii\right)$
4. $\left(i\right)$, $\left(ii\right)$ and $\left(iii\right)$

Q. A simple microscope is rated $5X$ for a normal relaxed eye. What will be its magnifying power for a relaxed farsighted eye whose near point is $40cm$?

1. $5$
2. $12.5$
3. $200$
4. $8$

Q.

What are the factors affecting the refractive index of a lens?

Q. Where should a pen be placed to form the largest image on retina? (and not be blurred)

1. Beyond near point
2. Between near point and eye
3. At near point
4. \N

Q. Find the maximum magnifying power of a compound microscope having a $25$ diopter lens as the objective, a $5$ diopter lens as the eyepiece and the separation $30\text{cm}$ between the two lenses. The least distance for clear vision is $25\text{cm}$.

1. $3.3$
2. $6.8$
3. $8.5$
4. $9.1$

Q. A simple microscope is rated $5\text{X}$ for a normal relaxed eye. What will be its magnifying power for a relaxed farsighted eye whose near point is $50\text{cm}$ ?

1. $5\text{X}$
2. $8\text{X}$
3. $10\text{X}$
4. $12\text{X}$

Q.

For which of the following colour, the magnifying power of a microscope will be maximum

1. White colour

2. Red colour

3. Violet colour

4. Yellow colour

Q. A spherical surface of radius of curvature R separates air (refractive index 1.0) from glass (refractive index 1.5). The center of curvature is in glass. A point object P placed in air is found to have a real image Q in the glass. The line PQ cuts the surface at a point O and PO = OQ. The distance PO is equal to

1. $R$
2. $3R$
3. $2R$
4. $5R$

Q. The eye can detect $5\times {40}^4$ photons $(m^{2}s{)}^{-1}$ of green light $(\lambda =5000\stackrel{o}{A})$, while ear can detect ${10}^{-13}W{m}^{-2}$. As a power detector, which is more sensitive and by what factor?

1. Ear is more sensitive by a factor of 5.00
2. Eye is more sensitive and by a factor of 5.00
3. Both are equally sensitive
4. Eye is more sensitive by a factor of ${10}^{-1}$