1) Take a V-stand and place a convex lens on this stand.
2) Imagine the principal axis of the lens.
, 3) Light a candle and ask your friend to take the candle far away from the lens
along the principal axis.
4) We use a screen because it forms a real image generally which will form on a screen. Real images cannot be seen with an eye.
5) Adjust the screen, on other side of lens until clear image form on it.
6) Measure the distance of the image from the stand and also measure the distance between the candle and stand of lens.
7) Now place the candle at a distance of 60 cm from the lens. Such as the flame of the candle lie on the principal axis of the lens.
8) Try to get an image of candle flame on the other side on a screen.
9) Adjust the screen till you get a clear image.
10) Measure the distance of image (u) from lens and record the value of u and v in the table.
11) Repeat this for various distances of images in all cases note it in the table.
From this we conclude that a convex lens forms both real and virtual image when object placed at various positions.