Draw a ray diagram in each of the following cases to show the formation of the image, when the object is placed :
(i) between optical centre and principal focus of a convex lens.
(ii) anywhere in front of a concave lens.
(iii) at 2F of a convex lens.
State the signs and values of magnifications in the above mentioned cases (i) and (ii).
(i) A ray diagram showing the formation of the image when the object is placed between optical centre $(C)$ and principal focus $(F)$ of a convex lens.
When an object is placed between optical centre $(C)$ and principal focus $(F)$ of a convex lens, then the image formed is virtual, erect, magnified, and in front of the lens.
In this case, since the image formed is virtual and erect so the sign of magnification will be positive $(+)$. Also, the image formed is magnified therefore the values of magnifications will be greater than one.
(ii) A ray diagram showing the formation of the image when the object is placed anywhere in front of a concave lens.
When an object is placed anywhere in front of a concave lens, then the image formed is virtual, erect, diminished, and in front of the lens.
In this case, since the image formed is virtual and erect so the sign of magnification will be positive $(+)$. Also, the image formed is diminished therefore the values of magnifications will be less than one.
(iii) A ray diagram showing the formation of the image when the object is placed at $2F$ of a convex lens.
When an object is placed at $2F$ of a convex lens, then the image formed is real, inverted, the same size as the object and behind the lens.
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- Draw a ray diagram in each of the following cases to show the formation of image, when the object is placed:(i) between optical centre and principal focus of a convex lens.(ii) anywhere in front of a concave lens.(iii) at 2F of a convex lens.State the signs and values of magnifications in the above mentioned cases (i) and (ii).
- Draw ray diagram to show the principal focus of a:(i) concave mirror(ii) convex mirror
- An object is placed at a distance equal to 2f in front of a convex lens. Draw a labelled ray diagram to show the formation of image. State two characteristics of the image formed.
- What happens after refraction, when :(i) a ray of light parallel to the principal axis passes through a concave lens?(ii) a ray of light falls on a convex lens while passing through its principal focus?(iii) a ray of light passes through the optical centre of a convex lens?
- (a) An object is placed 10 cm from a lens of focal length 5 cm. Draw the ray diagrams to show the formation of image if the lens is (i) converging, and (ii) perging.(b) State one practical use each of convex mirror, concave mirror, convex lens and concave lens.
- Describe with the help of a ray diagram the nature, size and position of the image formed when an object is placed in front of a convex lens between focus and optical centre. State three characteristics of the image formed.
- Describe with the help of a ray-diagram, the size, nature and position of the image formed by a convex lens when an object is placed beyond 2f in front of the lens.
- Describe with the help of a ray-diagram, the formation of image of a finite object placed in front of a convex lens between f and 2f. Give two characteristics of the image so formed.
- Draw a ray diagram to show the formation of a real magnified image by a convex lens. (In your sketch the position of object and image with respect to the principal focus of lens should be shown clearly).
- Where should an object be placed in front of a convex lens to get a real image of the size of the object?(a) At the principal focus of the lens(b) At twice the focal length(c) At infinity(d) Between the optical center of the lens and its principal focus.
- (a) An object is placed well outside the principal focus of a convex lens. Draw a ray diagram to show how the image is formed, and say whether the image is real or virtual.(b) What is the effect on the size and position of the image of moving the object (i) towards the lens, and (ii) away from the lens?
- (a) Draw ray-diagrams to show the formation of images when the object is placed in front of a concave mirror (converging mirror): (i) between its pole and focus (ii) between its centre of curvature and focusDescribe the nature, size and position of the image formed in each case.(b) State one use of concave mirror based on the formation of image as in case (i) above.
- Draw ray diagrams to represent the nature, position and relative size of the image formed by a convex lens for the object placed:(a) at $2F_1$,(b) between $F_1$ and the optical centre $O$ of the lens.Which of the above two cases shows the use of convex lens as a magnifying glass? Give reasons for your choice.
- (a) With the help of a labelled diagram explain how a convex lens converges a beam of parallel light rays. Mark the principal axis, optical centre, principal focus and focal length of the convex lens on the diagram.(b) State whether convex lens has a real focus or a virtual focus.(c) List some things that convex lens and concave mirror have in common.
- (a) Draw a ray diagram to show the formation of image of an object placed between infinity and the optical centre of a concave lens.(b) A concave lens of focal length 15 cm forms an image 10 cm from the lens. Calculatei. The distance of the object from the lens.ii. The magnification for the image formediii. The nature of the image formed.
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