Question

4. Calculate the position object should be located in order to have same image and object distance from optical centre of lense? (2) a) atf b) at 2f c) at f/2 d) at the centre of lense - 5. If you have 10 fringes on 1cm due to a difraction grating, with slit separation of 1mm and screen located at 0.9 m, what will be the wavelength of incident beam? (2) a) 11um b)111 um c)1.1 um d) 0.111 um

Answer 1

Solution :

(4) L. u het, the image distance be u, object distance be wa the focal length of the bens be f. ť Now, to be the image distance & object distance some on either side of the optical center, Hence, k -25 Hence, correct option is: (6) at af) 1 cm cool cm. There are 10 fringes in 1 cm. Hence, fringe width V = 10 Again, y = DA where D = 0.9m=90 cm is the alistance of the screen from the grating a = 1 mm = oil cm i slif seperation, and, as in the war relength of the light used. Da cool dxool 0.1*0.1 90 » nalilla 10-4 an all um. So, Hence, correct option is: 1(e) lol um