EXERCISE - 1D

An object 3.0 cm high is placed perpendicular to the principal axis of a concave lens of focal length 15.0 cm.
The image is formed at a distance of 10.0 cm from the lens. Calculate: size and nature of the image formed.

State whether $u$, $v$ and $f$ are positive or negative, when: the lens is convex and the image formed is virtual.
 

State whether $u$, $v$ and $f$ are positive or negative, when: the lens is concave.

Draw ray diagrams showing the image formation by a concave lens when an object is placed: between focus and twice the focal length of the lens.
 

Draw ray diagrams showing the image formation by a concave lens when an object is placed: beyond twice the focal length of the lens.

A student focussed the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle screen and the lens as under: Position of candle = $12.0 \mathrm{cm}$, Position of convex lens = $50.0 \mathrm{cm}$, Position of the screen = $88.0 \mathrm{cm}$. Where will the image be formed if he shifts the candle towards the lens at a position of $31.0 \mathrm{cm}$?

A student focussed the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle screen and the lens as under: Position of candle = $12.0 \mathrm{cm}$, Position of convex lens = $50.0 \mathrm{cm}$, Position of the screen = $88.0 \mathrm{cm}$. What will be the nature of the image formed if he shifts the candle beyond the position of $31.0 \mathrm{cm}$ towards the lens?

A student focussed the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle screen and the lens as under: Position of candle = $12.0 \mathrm{cm}$, Position of convex lens = $50.0 \mathrm{cm}$, Position of the screen = $88.0 \mathrm{cm}$. Draw a ray diagram to show the formation of the image when the candle is shifted beyond the position of $31.0 \mathrm{cm}$ towards the lens.