Concave Thin Lens Diverging Lens Virtual Focal Point

Concave Thin Lens Diverging Lens Virtual Focal Point

Concave Thin Lens Virtual Image

No matter where the object is: Image is always virtual, smaller and upright F F

The Human Eye Web Links: Eye lens, Vision and Eyesight Near Point – Closest distance the eye can focus on (about 25 cm when we are young) Far Point – Farthest distance the eye can focus on (should be )

Someone who is Nearsighted cannot focus on far away objects. (Their far point is not at infinity. ) Nearsightedness can be corrected with diverging lenses Here’s how it works

Ex: Without my contact lenses, I need to stand 35 cm or the less from TV in order to see it in focus. Find the focal length of the contact lenses that correct my vision.

Someone who is Farsighted cannot focus on objects too near. Farsightedness can be corrected with converging lenses Here’s how it works

Ex: The man has a near point of 48 cm. His reading glasses are 2. 0 cm from his eyes, and with them on, he can read the newspaper as close as 25 cm to his eyes. Find the focal length of his glasses

Lens Aberrations 1) Spherical Aberration Can you think of two ways that this problem could be eliminated?

2) Chromatic Aberration How to correct this problem? Compound (Achromatic) Lens Do mirrors ever experience Chromatic Aberration? A. Yes B. No

Two people who wear glasses are camping. One is nearsighted, and the other is farsighted. Whose glasses would be useful in starting a fire by focusing the sun’s rays? A. The nearsighted person B. The farsighted person C. Any piece of glass will do the trick

Try these problems A convex lens has a focal length of 5 cm. An object is placed 7 cm from the lens. Determine the image distance and the image size. A convex lens has a focal length of 10 cm. An object is placed 7 cm from the lens. Determine the image distance and the image size. A concave lens has a focal length of 8 cm. An object is placed 12 cm from the lens. Determine the image distance and the image size. A concave lens has a focal length of 12 cm. An object is placed 23 cm from the lens. Determine the image distance and the image size.

If the image of the book is 5. 0 cm below the lens, find the focal length of the lens. Challenge problem… Hint di = -(f-5) cm Solve a quadratic to find f… lens 13 cm book

Sign conventions for Lenses Focal length (f) + converging Object distance (do) + object on the left - diverging Image distance (di) Magnification (m) + image on the right (real) + upright - image on the left (virtual) - inverted