मराठी
महाराष्ट्र राज्य शिक्षण मंडळएस.एस.सी (इंग्रजी माध्यम) इयत्ता १० वी

Surabhi from Std. X Uses Spectacle. the Powr of the Lenses in Her Spectacle is 0.5 D. Answer the Following Questions from the Given Information - Science and Technology 1

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प्रश्न

Surabhi from std. X uses spectacle. The power of the lenses in her spectacle is 0.5 D.

Answer the following questions from the given information:

  1. Identify the type of lenses used in her spectacle.
  2. Identify the defect of vision Surabhi is suffering from.
  3. Find the focal length of the lenses used in her spectacle.
थोडक्यात उत्तर
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उत्तर

1) The power is positive hence the convex lens
2) Hypermetropia
3) `"P" =1/"F"`

`"f" = 1/"P" = 1/0.5 = 2 "m"`
= 200 cm

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2018-2019 (March) Set 1

संबंधित प्रश्‍न

A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?


What is the focal length of a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 cm? Is the system a converging or a diverging lens? Ignore thickness of the lenses.


Consider two statements A and B given below:
A: real image is always inverted
B:  virtual image is always erect
Out of these two statements:


Which one of the following materials cannot be used to make a lens?


Name the physical quantity whose unit is dioptre.


Which type of lens has (a) a positive power, and (b) a negative power?


Which has more power : a thick convex lens or a thin convex lens, made of the same glass? Give reason for your choice.


A diverging lens has focal length of 3 cm. Calculate the power. 


What is the nature of a lens having a power of + 0.5 D?


What is the nature of a lens whose power is, −4 D?


The optician's prescription for a spectacle lens is marked +0.5 D. What is the:
(a) nature of spectacle lens?
(b) focal length of spectacle lens?


An object of height 4 cm is placed at a distance of 15 cm in front of a concave lens of power, −10 dioptres. Find the size of the image.


An object of height 4.25 mm is placed at a distance of 10 cm from a convex lens of power +5D. Find (i) the focal length of the lens, and (ii) the size of the image.


The power of a combination of two lenses X and Y is 5 D. If the focal length of lens X be 15 cm :
(a) calculate the focal length of lens Y.
(b) state the nature of lens Y.

 


A diverging lens has a focal length of 0.10 m. The power of this lens will be:


The power of a lens is +2.0D. Its focal length should be :


State the condition for the following  a ray passes undeviated through the lens .


Mohan obtained a sharp inverted image of a distant tree on the screen placed behind the lens. He then moved the screen and tried to look through the lens in the direction of the object. He would see: 

(1) a blurred image on the wall of the laboratory. 

(2) an erect image of the tree on the lens.

(3) no image as the screen has been removed 

(4) an inverted image of the tree at the focus of the lens.


A thin converging lens is formed with one surface convex and the other plane. Does the position of image depend on whether the convex surface or the plane surface faces the object?


A symmetric double convex lens in cut in two equal parts by a plane perpendicular to the principal axis. If the power of the original lens was 4 D, the power a cut-lens will be


A symmetric double convex lens is cut in two equal parts by a plane containing the principal axis. If the power of the original lens was 4 D, the power of a divided lens will be


A pin of length 2.00 cm is placed perpendicular to the principal axis of a converging lens. An inverted image of size 1.00 cm is formed at a distance of 40.0 cm from the pin. Find the focal length of the lens and its distance from the pin.


The power of a lens is +2.0 D. Find its focal length and state the kind of lens.


The following diagram shows the object O and the image I formed by a lens. Copy the diagram and on it mark the positions of the lens LL’ and focus (F). Name the lens.


Complete the diagram to show the formation of the image of the object AB.

(i) Name the Lens LL’.
(ii) Where is the image of the object AB formed?
(iii) State three characteristics of the image.


A convex lens is of focal length 20 cm. Find its power.


The power of the magnifying glass depends on the distance of the magnifying glass from object.


Increase in the converging power of eye lens cause ‘hypermetropia'


Assertion and reasoning type

  1. Assertion: Myopia is due to the increase in the converging power of eye lens.
  2. Reason: Myopia can be corrected with the help of concave lens.

The above lens has a focal length of 10 cm. The object of height 2 mm is placed at a distance of 5 cm from the pole. Find the height of the image.


Define power of a lens. What is its unit? One student uses a lens of focal length 50 cm and another of –50 cm. What is the nature of the lens and its power used by each of them?


The focal length of a concave lens is 20 cm. The focal length of a convex lens is 25 cm. These two are placed in contact with each other. What is the power of the combination? Is it diverging, converging or undeviating in nature?


An object is placed in front of a converging lens. Obtain the conditions under which the magnification produced by the lens is

  1. negative and
  2. positive.

A point object is placed at O in front of a glass sphere as shown in figure.

Show the formation of the image by the sphere.


When monochromatic red light is used instead of blue light in a convex lens, its focal length will ______.


An object is kept at a distance of 1m from a lens of power +2D:

  1. Identify the type of lens.
  2. Calculate its focal length and distance of the image formed.

In what unit is the power of a lens expressed?


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