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प्रश्न
Fill in the following blank with suitable word:
For converging lenses, the power is __________ while for diverging lenses, the power is ___________.
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उत्तर
For converging lenses, the power is positive while for diverging lenses, the power is negative.
संबंधित प्रश्न
What is meant by a power of a lens? Define its SI unit.
What does sign of power (+ve or –ve) indicate?
The lens mentioned in 6(b) above is of focal length 25cm. Calculate the power of the lens.
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 type of lens has a positive 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.
A lens has a focal length of, −10 cm. What is the power of the lens and what is its nature?
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?
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:
The power of a lens is + 1.0 D is :
How does focal length of a lens change when red light incident on it is replaced by violet light? Give reason for your answer.
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 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 double convex lens has focal length 25 cm. The radius of curvature of one of the surfaces is double of the other. Find the radii, if the refractive index of the material of the lens is 1.5.
How is accommodation produced?
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 ______.
An object is placed in front of a converging lens. Obtain the conditions under which the magnification produced by the lens is
- negative and
- positive.
The lens of power + 1·0 D is ______.
One dioptre is the power of a lens whose focal length is:
The power of a lens in dioptres is given by:
The power of a lens placed in a medium is given by:
A positive power of a lens indicates a:
A greater numerical value of the power of a lens means:
When a lens is placed in a liquid, the total power of the lens is:
A concave lens has:
