Q18 of 27 Page 132

Figure Q- 18 shows a point light source and its image produced by a lens with an optical axis N1N2. Find the position of the lens and is foci using a ray diagram. (AS5)

From the given points we can infer that the image formed will be magnified according to the heights of the dots. Moreover, the image should be erect. So now we have to select the lens. For concave lens only, diminished image will be formed of the object. Thus, we cannot take the concave lens and hence convex lens is the only option. In convex lens, there is only one position of the object where the image is erect & magnified that is the image should be between focus & O. This figure represents the opposite of the given figure.


More from this chapter

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16

Use the data obtained by activity-2 in table-1 of this lesson and draws the graphs of u vs v and 1/u vs 1/v. (AS5)

 17

Figure Q-17 shows ray AB that has passed through a divergent lens. Construct the path of the ray up to the lens if the position of its foci is known. (AS5)

 19

Find the focus by drawing a ray diagram using the position of source S and the image S’ given in the figure Q-I9. (AS5)

 20

A parallel beam of rays is incident on a convergent lens with a local length of 40cm. Where should a divergent lens with a focal length of 15 cm be placed for the beam of rays to remain parallel after passing through the two lenses? Draw a ray diagram. (AS5)