"A convex lens can form a magnified erect as well as magnified inverted image of an object placed in front of it." Draw ray diagram to justify this statement stating the position of the object with respect to the lens in each case.
An object of height 4 cm is placed at a distance of 20 cm from a concave lens of focal length 10cm. Use lens formula to determine the position of the image formed.

Explanation

A convex lens can form a magnified erect image when the object is placed betweent eh optical centre and principal focus of the convex lens (i.e., between O and F').

A convex lens can form a magnified inverted image when the object is placed between focus and the centre of curvature ( i.e., between F' and 2F').

Object height, h= 4 cm, Object distance, `u= -20 cm`
Nature of the lens `=` concave lens , Focal length `= f = - 10 cm`
Image distance , ` v= ?`
According to the lens formuls,
`(1)/(f)=(1)/(v) -(1)/(u)implies (1)/(v) = (1)/(f)+(1)/(u)`
`(1)/(v)=(1)/(-10)+(1)/(-20)implies (-2-1)/(20)=(-3)/(20) :. v= (-20)/(3)= -6.66 cm`
So, image is formed at 6.66 cm from lens side. Image is erect, virtual and diminsihed in size.