Question -
Answer -
Focal length of the objective lens,┬аfo┬а= 140 cm
Focal length of the eyepiece,┬аfe┬а= 5 cm
(a)┬аIn normal adjustment, the separation between theobjective lens and the eyepiece┬а
(b)┬аHeight of the tower,┬аh1┬а= 100 m
Distance of the tower (object) from thetelescope,┬аu┬а= 3 km = 3000 m
The angle subtended by thetower at the telescope is given as:
The angle subtended by theimage produced by the objective lens is given as:
Where,
h2┬а= Height of theimage of the tower formed by the objective lens
Therefore, the objectivelens forms a 4.7 cm tall image of the tower.
(c)┬аImage is formed at adistance,┬аd┬а= 25 cm
The magnification of theeyepiece is given by the relation:
Height of the final image
Hence,the height of the final image of the tower is 28.2 cm.