thin lenses project
TRANSCRIPT
Thin LensesBy: Olivia and Noelia
Objectives: (Thin Lenses 14.2)
• Compare diverging and converging lenses
• Relate concepts to eyeglasses and contact lenses
• Describe the positioning of lenses in compound microscopes and telescopes
Introduction
Hey ya’ll, today we will be covering lesson 14, section 2 over Thin Lenses. Hopefully by the end of this lesson, you will better understand…
• Thin Lenses
• Diverging and converging lenses
• Ray diagrams
Introduction Continued...
Hopefully ya’ll will also better understand…
• What type of lenses are used for the correction of nearsightedness and farsightedness
• How lenses are positioned in compound microscopes and telescopes
Information
• Lenses use refraction, unlike mirrors that use reflection.
• Refraction is simply the bending of light as it passes from one substance to another.
• A lens forms an image by bending rays of light that pass through it.
Diverging Lenses
• Also known as concave lens
• These lens are thinner in the middle, causing the rays of light to appear to come from a single point
• After light is passed through these lenses, it bends and splits (diverges)
Diverging Lenses Continued...
Converging Lenses
• Also known as convex lens
• These lenses are thicker in the middle, causing rays of light that are initially parallel to meet at a single point called the focal point
• After light is passed through these lenses, it bends and comes together at one point (focal point)
Converging Lenses Continued...
Ray Diagrams
Nearsightedness Correction
o When the eye is too long.
o The focus point is in front of the retina, instead of sharply being focused in.
Nearsightedness Correction
• To correct this problem diverging lenses are used.
Farsightedness Correction
• When the eye is too short, and the focus point is behind the retina
Farsightedness Correction
• To correct this problem converging lenses are used
Compound Telescopes
• A telescope is an instrument made to make distant objects appear nearer.
• It contains an arrangement of lenses, by which rays of light are collected
and focused and the resulting image magnified.
Compound Microscopes
• A microscope is an instrument that is used for viewing very small objects, such as animal or plant cells, which are typically magnified several hundred times.
• A microscope has
two main lenses
(ocular and objective)
Questions
1) What is another name for diverging lenses?
• Concave
2) How many lenses does a microscope have? What are they called?
• Two (ocular and objective)
3) What kind of lens are used to correct farsightedness?
• Converging
Questions Continued...
4) Where is the focus point located on a near-sighted person’s eye?
• In front of the retina
5) In order for a compound telescope to produce an image, what kind of lenses must be present?
• Converging
Questions Continued...
6) Which lenses makes light disperse after being bent and passed through?
• Diverging
7) True/False...Farsightedness people’s focus point is located behind the retina?
• True
8) Which instrument is designed to make distant objects appear nearer?
• A telescope
Work Sitedstaff, M. (2012, March 3). Definition. Mayo Clinic. Retrieved October 29, 2013, from
http://www.mayoclinic.com/health/nearsightedness/DS00528
staff, M. (2012, April 24). Definition. Mayo Clinic. Retrieved October 29, 2013, from http://www.mayoclinic.com/health/farsightedness/DS00527
Diverging Lenses - Ray Diagrams. (n.d.). Diverging Lenses - Ray Diagrams. Retrieved October 29, 2013, from http://www.physicsclassroom.com/Class/refrn/U14l5ea.cfm
Converging Lenses - Object-Image Relations. (n.d.). Converging Lenses - Object-Image Relations. Retrieved October 29, 2013, from http://www.physicsclassroom.com/Class/refrn/u14l5db.cfm
How a Compound Light Microscope Works. (n.d.). Compound Light Microscope: How It Works. Retrieved October 29, 2013, from http://www.indepthinfo.com/microscopes/compound.htm
Hewitt, P. (2009). Lenses. Conceptual Physics The High School Program (pp. 602 - 616). Upper Saddle River : Pearson Education .