A thin converging lens forms a :
(i) Real magnified image
(ii) Virtual magnified image of an object placed in front of it
(a) Write the positions of the objects in each case
(b) How will the following be affected on cutting this lens into two halves along the principle X axis?
(i)Focal length, (ii)intensity of the image formed by half lens
a.
A converging lens will form a real and magnified image when the object distance is between the focal length and double of the focal length of the lens.
b.
A virtual and magnified image is formed when the object lies between focus and the pole of the lens. If the object is at the focus the virtual image is infinitely large.
c.
On cutting the lens into two half along the principal axis will not affect the focal length of the lens.
d.
The intensity of a lens is given by the relation, I = A/f2
Where, ‘f’ is the focal length and ‘A’ is the circular area of the lens.
As the lens is halved along its principal axis, the circular area of the lens will also be halved.
So, the resultant intensity will be, I/ = (A/2)/f2 = I/2
Thus, intensity of the image is halved.