One half of a convex lens of focal length 10 cm is covered with a black paper. Can such a lens produce an image of a complete object placed at a distance of 30 cm from the lens?Draw a ray diagram to justify your answer. A 4 can tall objectis placed perpendicular to the perpendicular to the principal axis of a convex lens of focal length 20 cm. The distince of the object from the less is 15 cm. Find nature, position and size of the image.

One half of a convex lens of focal length 10 cm is covered with a blac

1.	One half of a convex lens of focal length 10 cm is covered with a black paper. Can such a lens produce an image of a complete object placed at a distance of 30 cm from the lens?Draw a ray diagram to justify your answer. A 4 can tall objectis placed perpendicular to the perpendicular to the principal axis of a convex lens of focal length 20 cm. The distince of the object from the less is 15 cm. Find nature, position and size of the image.
Answer» Solution :(i) Yes . If a convex lens of focal length 10 cm is convered one half with a BLACK paper , it can produce an image of the complete object between `F_(2) and 2 F_(2)`. The rays of light coming from the object get refrected by the upper half of the lens. The image formed will be real, inverted and diminished . (ii) Object height,` h_(1) = 4 cm `Focal length, f + 20 cmObject DISTANCE, u = - 15 Imagedistance, V = ? Image height , `h_(2) = ?` By lens formula, `(1)/(f) = (1)/(v) - (1)/(u)rArr(1)/(v) = (1)/(f) + (1)/(u) = (1)/(+20) + (1)/(-15)= (1)/(20) - (1)/(15) rArr(1)/(v) = (3-4)/(60) = (-1)/(60)` Positive sing of `h_(2)` SHOWS that the image is erect. Therefore, a virtual, erect, magnified (16 cm) image will be formed at a distance of 60 cm on the same side as of the object by the convex lens.