Download Lens Webquest and Virtual Lab File

Mirror and Lenses Virtual Lab
Objectives of this activity:
Describe the shape and refractive properties of a convex and concave lens
Explain how lenses are used to correct vision
Describe and identify the conditions of nearsightedness and farsightedness
Apply knowledge of the properties of convex and concave lenses to correct vision disorders
This Virtual Lab and Webquest can be accessed at the following website:
http://www.glencoe.com/sites/common_assets/science/virtual_labs/E11/E11.html
Read the box on the left and fill in the blanks below as you read along:
How are lenses used to correct vision?
A _____________ is a type of transparent material that bends light. Most manufactured lenses are made of
glass or plastic. The bending of light is called __________________. As parallel rays of light pass through a
lens, they are refracted in such a way that they either come together (__________________) or spread out
(____________________). The thicker and more curved the lens is, the more it will ___________________ light rays.
The point at which converging light rays meet is called the ______________________________.
The human eye contains its own __________________. In an eye with normal vision, this lens is able to focus
light rays on the ________________________, creating a clear image. Sometimes the lens of the eye cannot focus
properly, and this creates ___________________________________. __________________________________ is the inability of
the eye to focus on nearby objects, and ____________________________________ is the inability of the eye to focus
on far objects.
Lenses worn in front of the eye can ______________________ vision disorders by either spreading out or
bringing together _____________________________ enough so that the eye’s lens can focus them on the retina.
In this virtual lab you will examine the refractive properties of convex and concave lenses, and apply
these properties by selecting appropriate lenses to correct various vision disorders.
Procedure:
1. Click on the “Optics” button to read about how eyes and lenses work. Fill in the blanks as you read
along. Do this before you complete the activity as you might need this information to refer to
while you are working. Click the forward and back arrows to page through the information. Click
the “Close” button once you are finished.
Optics Information:
_______________________ lenses are thicker in the middle and thinner on the edges, and may be curved on one
or both sides. Convex lenses cause light rays to ____________________________________, or come together.
_______________________ lenses are thinner in the middle and thicker on the edges, and may be curved on one
or both sides. Concave lenses cause light rays to __________________________________, or spread apart.
The human eye contains a flexible _____________________________ lens that focuses light reflected from objects
onto the ________________________. The ___________________________ surrounding the eye change the shape of the
lens and allow it to focus properly, depending on how close or distant the object is. Rays that travel
through the lens converge at a ____________________________. All these focal points lie on a focal plane on the
_______________________________ of the eye (the retina). The image on the focal plane is upside-down, or
_______________________________. The brain _________________________________ the inverted image into the view we
see.
Sometimes the lens of the eye cannot __________________________ light properly on the retina. The
_______________________________ eye can see distant objects clearly, but nearby objects appear blurred.
Another type of farsightedness starts at about age 40, when the lens begins to lose ________________________
to focus on near objects, causing a need for reading lenses.
The nearsighted eye may be too long, and the focal point falls ________________________ of the retina. The
nearsighted eye can see close objects clearly, but distant objects appear blurred.
Lenses can correct vision problems by ____________________ light rays before they reach the eye, in effect
moving the focal point of the eye’s lens so that it falls upon the retina and creates a clear image.
_______________________ lenses cause light rays to converge and _________________________ the focal point for the
farsighted eye. _______________________ lenses cause light rays to diverge and _____________________ the focal
point for the nearsighted eye. ______________________ lenses cause greater refraction, so _______________________
lenses correct greater degrees of near- or farsightedness.
Procedures continued:
2. Click the “Focal Point” button to check the focal point of the patient’s eye. The diagram shows the
lens of the eye refracting a ray of light to a focal point in front of or behind the patients retina. Record
your findings.
3. Observe the patient’s view and the distance of the object, and determine whether the patient is
nearsighted or farsighted. Record the appropriate information in the spaces provided.
4. Click a lens and drag it in front of the patient’s eye. Look for changes in the patient’s vision. Click
the “Focal Point” button. If the lens corrects the patient’s vision, the focal point will fall on the
patient’s retina.
5. When you find the lens that gives the patient a clear view, record your findings.
6. Choose a new patient from the patient menu and repeat the above steps. Complete these steps
with 6 different patients.
7. Be sure to fill and complete all of the information for each patient.
Patient #1 :
Is the focal point in front of or behind the retina of the eye? _________________________________
Is this patient nearsighted or farsighted? ____________________________________________________________
What is the distance between the patient and the object? __________ What is the object? ___________________
Which type of lens corrected the patient vision, convex or concave? ______________________________________
Did you use the thin, medium thick, or thickest lens? ___________________________________________________
Patient #2 :
Is the focal point in front of or behind the retina of the eye? _________________________________
Is this patient nearsighted or farsighted? ____________________________________________________________
What is the distance between the patient and the object? __________ What is the object? ___________________
Which type of lens corrected the patient vision, convex or concave? ______________________________________
Did you use the thin, medium thick, or thickest lens? ___________________________________________________
Patient #3 :
Is the focal point in front of or behind the retina of the eye? _________________________________
Is this patient nearsighted or farsighted? ____________________________________________________________
What is the distance between the patient and the object? __________ What is the object? ___________________
Which type of lens corrected the patient vision, convex or concave? ______________________________________
Did you use the thin, medium thick, or thickest lens? ___________________________________________________
Patient #4 :
Is the focal point in front of or behind the retina of the eye? _________________________________
Is this patient nearsighted or farsighted? ____________________________________________________________
What is the distance between the patient and the object? __________ What is the object? ___________________
Which type of lens corrected the patient vision, convex or concave? ______________________________________
Did you use the thin, medium thick, or thickest lens? ___________________________________________________
Patient #5 :
Is the focal point in front of or behind the retina of the eye? _________________________________
Is this patient nearsighted or farsighted? ____________________________________________________________
What is the distance between the patient and the object? __________ What is the object? ___________________
Which type of lens corrected the patient vision, convex or concave? ______________________________________
Did you use the thin, medium thick, or thickest lens? ___________________________________________________
Patient #6 :
Is the focal point in front of or behind the retina of the eye? _________________________________
Is this patient nearsighted or farsighted? ____________________________________________________________
What is the distance between the patient and the object? __________ What is the object? ___________________
Which type of lens corrected the patient vision, convex or concave? ______________________________________
Did you use the thin, medium thick, or thickest lens? ___________________________________________________