An object of height 6 cm is placed perpendicular to the principal axis of a concave lens of focal length5 cm. Use lens formula to determine the position, size and nature of the image if the distance of the object from the lens is 10 cm.

An object of height 6 cm is placed perpendicular to the principal axis

1.	An object of height 6 cm is placed perpendicular to the principal axis of a concave lens of focal length5 cm. Use lens formula to determine the position, size and nature of the image if the distance of the object from the lens is 10 cm.
Answer» Solution :A CONCAVE lens always form a virtual and erect IMAGE on the same side of the OBJECT. Image distance v=? Focal length f=-5 cm Object distance u=-10 cm `1/f=1/v-1/u` `1/v=1/f+1/u` `=1/(-5)+1/(-10)` `=1/(-5)+1/(-10)` `=1/(-5)-1/10=(-1-2)/10` `=(-3)/10=3.3cm` `v=-3.3cm` `("Size of the image")/("Size of tbe object")=+v/u` `(h.)/h=(-3.3)/(-10)` `h/6=3.3/10` `h.=(6xx3.3)/10` `=(19.8)/10=1.98 cm` Size of the image is 1.98 cm