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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 +2D.
Calculate the focal length of a corrective lens having power +2.5 D.
What does sign of power (+ve or –ve) indicate?
How unit of power related to focal length of a lens?
A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.
(a) At what distance should the lens be held from the figure in order to view the squares distinctly with the maximum possible magnifying power?
(b) What is the magnification in this case?
(c) Is the magnification equal to the magnifying power in this case? Explain.
You have two lenses A and B of focal lengths +10 cm and –10 cm, respectively. State the nature and power of each lens. Which of the two lenses will form a virtual and magnified image of an object placed 8 cm from the lens? Draw a ray diagram to justify your answer
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
How is the power of a lens related to its focal length?
A converging lens has focal length of 50 mm. What is the power of the lens?
Fill in the following blank with suitable words :
The reciprocal of the focal length in metres gives you the _________ of the lens, which is measured in ___________.
Fill in the following blank with suitable word:
For converging lenses, the power is __________ while for diverging lenses, the power is ___________.
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.
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?
What do you understand by the power of a lens?
A converging lens has a focal length of 50 cm. The power of this lens is:
A diverging lens has a focal length of 0.10 m. The power of this lens will be:
How is the power of a lens related to its focal length?
Find the radius of curvature of the convex surface of a plano-convex lens, whose focal length is 0.3 m and the refractive index of the material of the lens is 1.5.
A normal eye is not able to see objects closer than 25 cm because
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
The power of a lens is +2.0 D. Find its focal length and state the kind of lens.
Focal length : metre : : power of lens : _______
Find the power of a convex lens of focal length of + 25 cm.
Increase in the converging power of eye lens cause ‘hypermetropia'
Match the following:
| Column - I | Column - II | ||
| 1 | Retina | a | Path way of light |
| 2 | Pupil | b | Far point comes closer |
| 3 | Ciliary muscles | c | near point moves away |
| 4 | Myopia | d | Screen of the eye |
| 5 | Hypermetropia | e | Power of accommodation |
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?
The SI unit of the power of a lens is the:
The power of a lens in dioptres is given by:
A concave lens is a diverging lens whose focal length and power are both:
A greater numerical value of the power of a lens means:
When a lens is placed in a liquid, light refracts at:
The power of a lens of focal length \[f = 0.5\,m\] is:
A lens has a power of \[+2\,D\]. Its focal length is:
For a lens with \[f = +12\,cm\], \[R_1 = +10\,cm\] and \[R_2 = -15\,cm\], the lens maker's formula \[\frac{1}{f}=(n-1)\left(\frac{1}{R_1}-\frac{1}{R_2}\right)\] gives the refractive index of the glass as:
