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प्रश्न
In image formation from spherical mirrors, only paraxial rays are considered because they
विकल्प
are easy to handle geometrically
contain most of the intensity of the incident light
from nearly a point image of a point source
show minimum dispersion effect.
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उत्तर
form nearly a point image of a point source
Since, when reflected back, they meet at a single point forming a point image of a point source.
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संबंधित प्रश्न
A small candle, 2.5 cm in size is placed at 27 cm in front of a concave mirror of radius of curvature 36 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? Describe the nature and size of the image. If the candle is moved closer to the mirror, how would the screen have to be moved?
The image of an extended object, placed perpendicular to the principal axis of a mirror, will be erect if
(a) the object and the image are both real
(b) the object and the image are both virtual
(c) the object is real but the image is virtual
(d) the object is virtual but the image is real.
Light is incident from glass (μ = 1.5) to air. Sketch the variation of the angle of deviation δ with the angle of incident i for 0 < i < 90°.
A spherical surface of radius 30 cm separates two transparent media A and B with refractive indices 1.33 and 1.48 respectively. The medium A is on the convex side of the surface. Where should a point object be placed in medium A so that the paraxial rays become parallel after refraction at the surface?
A narrow pencil of parallel light is incident normally on a solid transparent sphere of radius r. What should be the refractive index is the pencil is to be focussed (a) at the surface of the sphere, (b) at the centre of the sphere.
Focal length of a mirror is given by ______.
According to the mirror equation, ______.
The intensity of a point source of light, S, placed at a distance d in front of a screen A, is I0 at the center of the screen. Find the light intensity at the center of the screen if a completely reflecting plane mirror M is placed at a distance d behind the source, as shown in the figure.
The radius of curvature of the curved surface of a plano-convex lens is 20 cm. If the refractive index of the material of the lens be 1.5, it will ______.
The direction of ray of light incident on a concave mirror is shown by PQ while directions in which the ray would travel after reflection is shown by four rays marked 1, 2, 3 and 4 (figure). Which of the four rays correctly shows the direction of reflected ray?
A short object of length L is placed along the principal axis of a concave mirror away from focus. The object distance is u. If the mirror has a focal length f, what will be the length of the image? You may take L << |v – f|.
A thin convex lens of focal length 25 cm is cut into two pieces 0.5 cm above the principal axis. The top part is placed at (0, 0) and an object placed at (– 50 cm, 0). Find the coordinates of the image.
If an object is placed at a distance of 10 cm in front of a concave mirror of a focal length of 20 cm, the image formed will be ______.
Why does a car driver use a convex mirror as a rear-view mirror?
A lens of focal length f is divided into two equal parts and then these parts are put in a combination as shown in the figure below.
- What is the focal length of L1?
- What is the focal length of the final combination?
The geometric centre of a spherical mirror is called its:
Which of the following is a correct statement of one of the laws of reflection?
The angle of incidence is the angle between:
According to the laws of reflection, the incident ray, the reflected ray, and the normal to the reflecting surface at the point of incidence:
