### Theory:

We studied the converging and diverging nature of spherical lenses. Now let us look at activity that explains the image formed by the concave and convex mirrors.
• Take a convex lens.
• Draw five parallel straight lines on a long table with chalk, so that the distance between the successive lines equals the focal length of the lens.
• Place the lens on a lens stand.
• Place it so that the optical centre of the lens is just over the line on the central line.
• The two lines on either side of the lens correspond to $$F$$ and $$2F$$ of the lens, respectively.
• Mark them with the appropriate letters, such as $$2$$${F}_{1}$, ${F}_{1}$, ${F}_{2}$, and 2${F}_{2}$. Place a burning candle far to the left of $$2$$${F}_{1}$.
• On a screen on the other side of the lens, get a clear, sharp image. Make a note of the image's nature, location, and relative size.
• Place the object behind $$2$$${F}_{1}$, between F1${F}_{1}$ and $$2$$${F}_{1}$ at ${F}_{1}$, and between ${F}_{1}$and O to repeat the activity.
• Make a list of your observations and tabulate them.
Image formation by convex lenses:

When an object is placed at infinity, a real image is formed at the principal focus. The size of the image is much smaller than that of the object.

Object at infinity

When an object is placed behind the centre of curvature (beyond C), a real and inverted image is formed between the centre of curvature and the principal focus. The size of the image is smaller than that of the object.

Object is placed behind the curvature

When an object is placed at the centre of curvature, a real and inverted image is formed at the other centre of curvature. The size of the image is the same as that of the object.

Object is placed at the center of curvature

When an object is placed in between the centre of curvature and principal focus, a real and inverted image is formed behind the centre of curvature. The size of the image is bigger than that of the object.

Object is placed in between the centre of curvature and principal focus

When an object is placed at the focus, a real image is formed at infinity. The size of the image is much larger than that of the object.

Object is placed at the focus

When an object is placed in between principal focus and optical centre, a virtual image is formed. The size of the image is larger than that of the object.

Object is placed in between principal focus and optical centre