LENS APPLICATIONS

13.5 – PG. 567 to 570

TYPES OF LENS APPLICATIONS

The Camera

The Movie Projector

TYPES OF LENS APPLICATIONS

The Magnifying Glass

The Compound Microscope

The Refracting Telescope

THE CAMERA

Produces a smaller, real image

Acts like converging lens, producing an inverted, real image as long as the object is at a distance greater then F’ (secondary principal of focus)

Takes light from large, distant objects and forms smaller, real images on film or the sensor in a digital camera

Digital cameras use a light-sensitive device made of silicon called a charge-coupled device (CCD), which replaces the film found in traditional cameras

How do Digital Cameras Work http://www.youtube.com/watch?v=9dXlok8PMLo

THE MOVIE PROJECTOR

A movie projector acts like the opposite of a camera

Projectors take a small object (film) and projects a large, inverted, real image on the screen

The image is larger than the object, meaning the film must be located between F’ and 2F’

Film must be loaded into the projector upside down so that what you see on the movie screen is upright

Overhead projectors work in a similar way

How a Movie Projectors Works http://www.youtube.com/watch?v=Ca_4dN8jrbg

THE MAGNIFYING GLASS

The simplest optical device is the magnifying glass, also known as a simple microscope

It is a converging lens, where the object is located between F’ and the lens and does not produce a real image at the object location

Refracted rays spread apart or diverge, creating a larger, upright, virtual image on the same side of the lens as the object

The human brain extends these rays backwards and produces an enlarged, virtual image located on the same side of the lens as the object

Giant Magnifying Glass http://www.youtube.com/watch?v=ljiTNRiLh-o

THE COMPOUND MICROSCOPE

An arrangement of two converging lenses that produces two enlarged, inverted images: one real and one virtual

The real image is formed by the objective lens and appears in the body tube of the microscope, therefore you do not actually see this image

The virtual image is formed by the eyepiece lens; this larger, virtual image is the image you actually see

Explaining Microscopeshttp://www.youtube.com/watch?v=ILZEOnQ_gl

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THE REFRACTING TELESCOPE

Same principal as compound microscope, difference being that the object is much farther away

Object in a refracting telescope is so far beyond 2F’ that incident rays passing through the objective lens are considered to be parallel

Produces two enlarged, inverted images: one real image (located in tube of telescope so it cannot be seen) and one virtual image (image you do see)

How Refracting Telescopes Workhttp://www.youtube.com/watch?v=VzSjqNE2AH

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IN SUMMARY

A camera uses a converging lens to produce a smaller, inverted, real image of a large object; the object is beyond 2F’, and the real image is located between F & 2F in the camera body

A movie projector uses a converging lens to produce a larger, inverted, real image of a small object; the object (film strip) lies between F’ and 2F’, and the image is located beyond 2F

IN SUMMARYA magnifying glass, or simple microscope, is a

converging lens in which the object is located between the lens and F’. A larger, upright, virtual image is formed on the same side of the lens as the object

A compound microscope consists of two converging lenses and produces a larger, inverted, virtual image. The object is located close to the objective lens

A refracting telescope consists of two converging lenses and produces a larger, inverted, virtual image. The object is so far away from the objective lens that the incident rays that pass through the lens are essentially parallel