27 nov focal length of concave mirror depends on
In which case will the student get more accurate value of focal length? Thus, the focal length of a concave mirror can be estimated by obtaining a real image of a distant object at its focus. [NCERT] Answer: A thick convex lens has shorter focal length. The measuring scale should be parallel to the base of both the stands. Answer: The reason behind the blurred image is that the mirror is away from the object. [NCERT] Answer: Concave mirror is used as a shaving mirror or in vanity boxes, because when the object is placed between its focus and pole, the magnified, erect and virtual images of the object will be formed. What change do you expect, if the lens were rather thick? In such cookers, what should be the preferable position of food vessel for cooking? How do you calculate the total resistance of a parallel circuit? The mirror holder along with the mirror should be kept perpendicular to the measuring scale for precise measurements. A beam of light generally converges after reflection from its surface, hence it is also called convergent mirror (Fig. Answer: The nature of image formed in this experiment is as follows: Question 9. How does the size of the image vary as an object is moved from close to the pole to a large distance? Name this point. This point is called the centre of curvature of the spherical mirror. As the distance between the pole 0 of the concave mirror and the focus F is the focal length of the concave mirror. In reflector type solar cookers, special concave (parabolic) mirrors are used. Answer: It depends upon the focal length of the lens. The principal axis of the convex lens should be horizontal, i.e. What happens to a ray of light when it passes through the optical centre of a lens? Answer: When a ray of light passes through the optical centre of a lens, it goes without bending. Result From the above observations and calculations, the approximate value of focal length of the given convex lens is ………. 1). A concave mirror produces both real and virtual images, which can be upright or inverted. 4). The polished surface of the concave mirror and the distinct object should be facing each other. Which surface of a shining spoon should be polished, to use the spoon as a concave mirror? Aim To determine the focal length of concave mirror by obtaining the image of a distant object. There should not be any obstacle in the path of rays of light incident on the concave mirror. Least count of measuring scale may not be correctly noted. A double convex lens is simply called convex lens. Adjust the distance of screen, so that the image of the distant object is formed on it as given in the figure below. Which type of lens is used by the watchmakers, while repairing five parts of a wrist watch? If the lens used in the experiment is a plano-convex lens, then what is the radius of curvature of the plane surface? How can we find the focal length of a concave mirror, when the image is obtained by using a concave mirror? A concave mirror should be always placed near an open window. Answer: The radius of curvature of the plane surface of plano-convex lens is infinity. In a concave mirror, rays of light are parallel to its principal axis and meet at a single point on the principal axis, after reflection from the mirror (as shown in Fig. Hence, it is also called a converging mirror. Question 4. [NCERT] Answer: Question 2. Question 7. The mirror holder, along with the mirror, may not be kept perpendicular to the measuring scale. Question 15. Why? A concave mirror is a curved mirror that forms a part of a sphere and designed in such a way that rays of light falling on its shiny surface converge upon reflection. The size of the image can be bigger or smaller than the object. 4. This expression is valid for concave as well as convex spherical mirrors. Question 11. Question 14. In which case, will the student is closer to accurate value of focal length? [NCERT] Answer: A concave mirror is the spherical mirror with inward curved reflecting surface, whereas a convex mirror is the spherical mirror with outward curved reflecting surface. Is the centre of curvature a part of a spherical mirror? Answer: When parallel rays of light fall on a concave mirror along its axis, then the rays meet at a point infront of the mirror after reflection from it. Question 6. The image of the sun should never be seen directly with the naked eye or it should never be focussed with a convex lens on any part of the body, paper or any inflammable material as it can burn. All u, v and f should be according to sign convention. cm, Focal length for first object (f1) = ………… m Focal length for second object (f2) = ………….. m Focal length for third object (f3) = …………. This point is one of the two foci of the lens. Why do we obtain blurred image from a concave mirror sometimes? Comment in support of your answer. The measuring scale may not be parallel to the base of both the stands. The nature, size, and position of the image depend on the position of the object. Actually, this spot of light is the image of the Sun on the sheet of paper. Answer: The surface of the spoon which is bulged outward should be polished to use the spoon as a concave mirror.
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