# Subject: PHYSICS Topic: Convex lens Light refraction in Prism Ray diagram of a convex lens Ray diagram illustrating graphical construction rules of a.

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Subject: PHYSICS Topic: Convex lens

Light refraction in Prism Ray diagram of a convex lens Ray diagram illustrating graphical construction rules of a convex lens Simulation of the ray diagram The six special case of convex lens Daily applications of convex lens Table of content

Convex lens teaching flow chart

The light rays converge after passing through the prisms!! In what way do the light rays pass through the prisms? QUESTION TIME Light rays passing through two prisms

QUESTION TIME The light rays converge!!

AGAIN!!! The light rays also converge to the same point! QUESTION TIME

Will the light rays still converge if we continue to cut the prisms? NO YES NO

Convex Lens thickest in the centre bends light inwards ä äconverging lens

Which of the above is/are convex lens(es)? A B CD A & C

F F’ C f F: Focus Convex lens C: Optical Center f = focal length (FC) Principal axis Terminology of Convex lens F: Focus f = focal length (FC) C: Optical Center Principal axis

    The light ray parallel to the principal axis  The light ray through the Optical Center C  The light ray through the focus F F F C    is refracted parallel to the principal axis. is refracted through the focus F. passes straight through the lens. Convex lens Construction Rules Now, we are going to find the image of an object formed by a convex lens by using these rules.

Classwork By using the three construction rules of convex lens, draw a ray diagram of an object with object distance u = 15 cm. (Assume the focal length of the convex lens is 10 cm.) Can you find the image distance? By using the three construction rules of convex lens, draw a ray diagram of an object with object distance u = 15 cm. (Assume the focal length of the convex lens is 10 cm.) Can you find the image distance? Answer

Converging Lens Simulation Converging Lens Simulation

When the object distance is larger than 2f, do you know the image position? Object Image 2F QUESTION TIME Case 1: Object distance >2f Object Image

Magnified / Diminished / Same as the object Virtual / Real Erect / Inverted Virtual / Real Magnified / Diminished / Same as the object Erect / Inverted Between the position of F and 2F on the other side of the object. Position of image: Descriptions of the image: Object distance >2f

Object Image 2F QUESTION TIME Case 2: Object distance = 2f Object Image

Magnified / Diminished / Same as the object Virtual / Real Erect / Inverted Virtual / Real Magnified / Diminished / Same as the object Descriptions of the image: Object distance = 2f At the position of 2F on the other side of the object. Position of image:

Object Image 2F QUESTION TIME Case 3: Object distance between f and 2f Object Image

Descriptions of the image: Object distance between f and 2f Image distance > 2f on the other side of the object. Erect / Inverted Virtual / Real Magnified / Diminished / Same as the object Magnified / Diminished / Same as the object Position of image:

Object Where is the image? 2F Case 4: Object distance = f Object

Descriptions of the image: Object distance = f Position of image: Image forms at infinity.

Object Image 2F QUESTION TIME Case 5: Object distance < f Image Object

Descriptions of the image: Object distance < f On the same side of the object. Erect / Inverted Virtual / Real Magnified / Diminished / Same as the object Magnified / Diminished / Same as the object Position of image:

Case 6: Very large object at infinity For a very large image at infinity: Convex lens The light rays are nearly parallel to each other!

F F2F Do you know how parallel light rays are refracted? Case 6: Very large object at infinity Remember the construction rules of convex lens.

Formed at the focal plane Erect / Inverted Virtual / Real Magnified / Diminished / Same as the object Position of image: Magnified / Diminished / Same as the object Descriptions of the image: Object distance >2f

Formed at the focal plane Erect / Inverted Virtual / Real Magnified / Diminished / Same as the object Position of image: Magnified / Diminished / Same as the object Descriptions of the image: Object distance >2f

Application of Convex lens Camera Magnifying glass

The End

By using the three construction rules of convex lens, draw a ray diagram of an object with object distance u = 25 cm and height 10 cm. (Assume the focal length of the convex lens is 10 cm.) u = 25 cm 10 cm 25 cm F F C 2F Object Image

Focus Focal plane Explanation of focal plane

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