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प्रश्न
The power of the magnifying glass depends on the distance of the magnifying glass from object.
पर्याय
True
Wrong
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उत्तर
The power of the magnifying glass depends on the distance of the magnifying glass from object- Wrong
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संबंधित प्रश्न
Calculate the focal length of a corrective lens having power +2.5 D.
The lens mentioned in 6(b) above is of focal length 25cm. Calculate the power of the lens.
Kavita from 10th is using spectacles. The power of the lenses in her spectacles is –2.5 dioptre. Answer the following questions:
1) Which lenses are used in her spectacles?
2) State the defect of vision Kavita is suffering from.
3) Find the focal length of the lenses used in her spectacles
A student uses a lens of focal length 40 cm and another of –20 cm. Write the nature and power of each lens
Give the usual name for the following:
A point inside a lens through which the light passes undeviated.
Which one of the following materials cannot be used to make a lens?
What is the power of a convex lens lens whose focal length is 80 cm?
The power of a lens is, −2 D. What is its focal length?
What is the nature of a lens having a power of + 0.5 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?
A convex lens of power 5 D and a concave lens of power 7.5 D are placed in contact with each other. What is the :
(a) power of this combination of lenses?
(b) focal length of this combination of lenses?
A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are placed in close contact with one another.
(a) What is the power of this combination?
(b) What is the focal length of this combination?
(c) Is this combination converging or diverging?
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.
What do you understand by the power of a lens? Name one factor on which the power of a lens depends.
What is the unit of power of a lens? Define the unit of power of a lens.
The power of a lens is +2.0D. Its focal length should be :
State the condition for the following a lens has both its focal lengths equal .
State the condition for the following a ray passes undeviated through the lens .
How is the sign (+ or -) of power of a lens related to its divergent or convergent action?
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.
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:
- Identify the type of lenses used in her spectacle.
- Identify the defect of vision Surabhi is suffering from.
- Find the focal length of the lenses used in her spectacle.
How is accommodation produced?
A lens forms an upright and diminished image of an object, irrespective of its position. What kind of lens is this? Draw an outline ray diagram to show the formation of the image. State the position and one more characteristic of the image.
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.
Focal length : metre : : power of lens : _______
According to Rayleigh’s scattering law, the amount of scattering of light is inversely proportional to the fourth power of its ______.
The power of lens depends on the focal length of the lens
Assertion and reasoning type
- Assertion: Myopia is due to the increase in the converging power of eye lens.
- Reason: Myopia can be corrected with the help of concave lens.
A convex lens with radii of curvature R1 = R2 is immersed in water. Assuming that the refractive indices of glass and water are 3/2 and 4/3 respectively, its focal length f1 in comparison to that in air, f, is ______.
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.
The same size images are formed by a convex lens when the object is placed at 20 cm or at 10 cm from the lens. The focal length of convex lens is ______ cm.
The focal length of a double convex lens is equal to the radius of curvature of either surface. What is the refractive index of its material?
In what unit is the power of a lens expressed?
