Resource Lesson
Thin Lens Equation
Printer Friendly Version
The thin lens equation is stated as follows:
where
d
_{o}
is the distance (measured along the axis) from the object to the center of the lens
d
_{i}
is the distance (measured along the axis) from the image to the center of the lens
f is the focal length of the lens
The expression 1/f in called the
power of a lens
. It is measured in Diopters, where 1 D = 1 m
^{-1}
.
When using this equation, signs are very important:
d
_{o}
positive
when the object is placed "in front of the lens"
d
_{i}
positive
when real images are formed (inverted, "behind the lens")
d
_{i}
negative
when virtual images are formed (upright, "in front of the lens")
f
positive
when the lens is
converging
f
negative
when the lens is
diverging
Remember that d
_{o}
, d
_{i}
, and f must be measured in the same unit - usually meters is preferred.
The following formula is used to calculate the magnification of an image:
If a problem states that a real image is formed that is twice as large as an object, then you would use the relationship d
_{i}
=
+
2d
_{o}
in the thin lens equation. If a problem states that a virtual image is formed that is twice as large as the object, then you would use the relationship that d
_{i}
=
−
2d
_{o}
.
Refer to the following information for the next three questions.
Suppose you are initially given a converging lens, made from crown glass, that has a focal length of +0.10 meter.
If this lens is to be used in air, which cross-sectional figure best represents its shape?
An object is placed 0.30 meter from the lens in the previous question. How far from the lens will the image of this object be formed?
Suppose this 0.800-meter tall object is now placed 0.20 meter in front of a second converging lens. If the distance of the image from the lens is 0.40 meter, then the height of the image is
Refer to the following information for the next four questions.
Suppose you are now given a double concave lens, also made from crown glass, that has a focal length of −0.10 meter.
Which cross-sectional figure best represents its shape?
This
diverging
lens can form only form ____ images.
An object is placed 0.20 meter from this diverging lens. How far from the lens will the image of the object be formed?
If the object in the previous question was 4.5 centimeters tall, how tall is its image?
Related Documents
Lab:
Labs -
A Simple Microscope
Labs -
Blank Ray Diagrams for Converging Lenses
Labs -
Blank Ray Diagrams for Converging, Concave, Mirrors
Labs -
Blank Ray Diagrams for Diverging Lenses
Labs -
Blank Ray Diagrams for Diverging, Convex, Mirrors
Labs -
Determining the Focal Length of a Converging Lens
Labs -
Index of Refraction: Glass
Labs -
Index of Refraction: Water
Labs -
Least Time Activity
Labs -
Man and the Mirror
Labs -
Man and the Mirror: Sample Ray Diagram
Labs -
Ray Diagrams for Converging Lenses
Labs -
Ray Diagrams for Converging Mirrors
Labs -
Ray Diagrams for Diverging Lenses
Labs -
Ray Diagrams for Diverging Mirrors
Labs -
Reflections of a Triangle
Labs -
Spherical Mirror Lab
Labs -
Student Lens Lab
Labs -
Target Practice - Revised
Resource Lesson:
RL -
A Derivation of Snell's Law
RL -
Converging Lens Examples
RL -
Converging Lenses
RL -
Demonstration: Infinite Images
RL -
Demonstration: Real Images
RL -
Demonstration: Virtual Images
RL -
Dispersion
RL -
Diverging Lenses
RL -
Double Lens Systems
RL -
Lensmaker Equation
RL -
Mirror Equation
RL -
Properties of Plane Mirrors
RL -
Refraction of Light
RL -
Refraction Phenomena
RL -
Snell's Law
RL -
Snell's Law: Derivation
RL -
Spherical Mirrors
Review:
REV -
Drill: Reflection and Mirrors
REV -
Mirror Properties
REV -
Physics I Honors: 2nd 9-week notebook
REV -
Physics I: 2nd 9-week notebook
REV -
Spherical Lens Properties
Worksheet:
APP -
Enlightened
APP -
Reflections
APP -
The Librarian
APP -
The Starlet
CP -
Lenses
CP -
Plane Mirror Reflections
CP -
Refraction of Light
CP -
Snell's Law
CP -
Snell's Law
NT -
Image Distances
NT -
Laser Fishing
NT -
Mirror Height
NT -
Mirror Length
NT -
Reflection
NT -
Underwater Vision
WS -
An Extension of Snell's Law
WS -
Basic Principles of Refraction
WS -
Converging Lens Vocabulary
WS -
Diverging Lens Vocabulary
WS -
Lensmaker Equation
WS -
Plane Mirror Reflections
WS -
Refraction and Critical Angles
WS -
Refraction Phenomena
WS -
Refraction Through a Circular Disk
WS -
Refraction Through a Glass Plate
WS -
Refraction Through a Triangle
WS -
Snell's Law Calculations
WS -
Spherical Mirror Equation #1
WS -
Spherical Mirror Equation #2
WS -
Spherical Mirrors: Image Patterns
WS -
Thin Lens Equation #1: Converging Lenses
WS -
Thin Lens Equation #2: Converging Lenses
WS -
Thin Lens Equation #3: Both Types
WS -
Thin Lens Equation #4: Both Types
WS -
Two-Lens Worksheet
WS -
Two-Mirror Worksheet
TB -
27B: Properties of Light and Refraction
TB -
Refraction Phenomena Reading Questions
PhysicsLAB
Copyright © 1997-2019
Catharine H. Colwell
All rights reserved.
Application Programmer
Mark Acton