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
Give two characteristics of the virtual image formed by a convex lens.
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 ……………
Give two characteristics of the image formed by a concave lens.
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.