Solution

First of all we will find out the position of image. By the position of image we mean the distance of image from the lens. Here, object distance, u = -12 cm (it is to the left of lens) Image distance, v= ? (To be calculated) Focal length, f= +8 cm (It is a convex lens) Putting these values in the lens formula: 1/v - 1/u = 1/f we get : 1/v - 1/-12 = 1/8 1/v =1/24 So, objective distance, v =+24 cm Thus, the image is formed at a distance of 24 cm from the convex lens. The plus sign for image distance shows that the image is formed on the right side of the convex lens. Only a real and inverted image is formed on the right side of a convex lens, so the image formed is real and inverted. Let us calculate the magnification now. We know that for a lens: Magnification, m= v/u Here, image distance, = 24 cm Object distance =-12 cm So, m = 24 =12 Or m = -2 Since the value of magnification is more than 1 (it is 2), so the image is larger than the object or magnified. The minus sign for magnification shows that the image is formed below the principal axis. Hence the image is real and inverted. Let us calculate the size of the image by using the formula: m=h2/h1 Here, Magnification,m = -2 (found above) Height of object, /,= +7 cm (Measured upwards)