Physics
Where must a point source of light be placed in front of a convex lens so as to obtain a parallel beam of light?
Related Questions
Complete the following sentences —
(a) An object is placed at a distance of more than 40 cm from a convex lens of focal length 20 cm. The image formed is real, inverted and ……………
(b) An object is placed at a distance 2f from a convex lens of focal length f. The size of the image formed is …………… that of the object.
(c) An object is placed at a distance 5 cm from a convex lens of focal length 10 cm. The image formed is virtual, upright and ……………
State whether the following statements are 'true' or 'false' by writing T/F against them.
(a) A convex lens has a divergent action and a concave lens has a convergent action.
(b) A concave lens, if kept at a proper distance from an object, can form its real image.
(c) A ray of light incident parallel to the principal axis of a lens, passes undeviated after refraction.
(d) A ray of light incident at the optical centre of a lens, passes undeviated after refraction.
(e) A concave lens forms a magnified or diminished image depending on the distance of an object from it.
What are the three principal rays that are drawn to construct the ray diagram for the image formed by a lens? Draw diagrams to support your answer.
In the diagrams below, XX' represents the principal axis, O the optical centre and F the focus of the lens. Complete the path of the rays A and B as they emerge out of the lens.
(a)
(b)
