Home Store Project Ideas Project Guide Ask An Expert Blog Careers Teachers Parents Students

A Magnifying Discovery

Difficulty
Time Required Very Short (≤ 1 day)
Prerequisites None
Material Availability Readily Available
Cost Very Low (under $20)
Safety No hazards

Abstract

Have you ever looked through a magnifying lens? Why do things look bigger when you look at them through the magnifying lens? Even though the object appears to get larger, it really stays the same size. Each lens has its own unique power of magnification, which can be measured with a ruler. How powerful is your lens?

Objective

In this experiment you will measure the apparent size of an object through a magnifying lens at different optical distances compared to the actual size of the object and discover a relationship between magnification and optical distance of a lens.

Credits

Sara Agee, Ph.D., Science Buddies

Cite This Page

MLA Style

Science Buddies Staff. "A Magnifying Discovery" Science Buddies. Science Buddies, 16 Nov. 2013. Web. 28 Aug. 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/Phys_p021.shtml>

APA Style

Science Buddies Staff. (2013, November 16). A Magnifying Discovery. Retrieved August 28, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/Phys_p021.shtml

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Last edit date: 2013-11-16

Introduction

Optics is the study of light and how light travels through different objects in different ways. Have you ever looked through a glass of water at something? You will notice that the object looks smaller through the glass than when you look through the air. This is because light travels differently through the glass and the water, causing the image to bend. Your eyes perceive this as a smaller object, even though your brain knows that the object is still the same size.

Physicists use the power of optics to make many different kinds of lenses to see different kinds of things better than the naked eye. Powerful telescopes can see far into space, making far away objects look closer and brighter. Powerful microscopes make tiny microscopic objects look much bigger, so that our eyes can see them in more detail. Many important discoveries in biology, chemistry, astronomy and other sciences have been made using the power of optics.

We also use optics in some things we use around the house. If you or your parents wear glasses, your doctor used optics to find a prescription for a lens to help you see better. If you like to go bird watching, then you have used a pair of binoculars to see birds in far off distances. A magnifying glass can be used to read tiny print, look at insects or to do a small hobby or craft.

One important factor for any lens is the power of magnification, a measurement of how much bigger the lens will make an object appear. When you use a magnifying lens to look at an object you can compare the actual size of the object (the real size of what you are looking at) to the apparent size of the object (the size your object looks like it is when you look through the lens). The magnification power of a lens can change depending upon how close the lens is to the object you are looking at, something called optical distance.

In this experiment, you can use a magnifying glass to make your own apparatus to discover the relationship between the optical distance and magnification of a lens.

Terms and Concepts

To do this project, you should do research that enables you to understand the following terms and concepts:

  • magnification
  • optics
  • lens
  • objective
  • optical distance
  • actual measurement
  • optical measurement

Bibliography

Materials and Equipment

  • large magnifying glass with a sturdy handle
  • ruler
  • permanent marker
  • scotch tape
  • wax paper
  • drinking straw
  • string or twisty tie
  • chunk of clay
  • small objects to measure (penny, typed or printed letter, bean, rice grain, etc.)

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Experimental Procedure

  1. Pull out a piece of scotch tape and place it on a non-stick surface, like a piece of wax paper.
  2. Using your ruler and permanent marker, mark points along the tape indicating centimeters and millimeters.
  3. Using scissors cut the length of the tape to fit inside the diameter of your magnifying lens.
  4. Stick the tape to the diameter of the lens. You will use this as a guide to make your optical measurements.

    Lens with Tape

  5. Now fold a drinking straw in half around the ruler. Tightly tie a piece of string around the ends of the straw so that it is tied around the ruler. The straw should slide up and down along the ruler without slipping.

    Ruler with Straw

  6. Now tape the handle of your magnifying glass onto the ends of the straw, so that the magnifying glass is perpendicular to the ruler. Jab the end of the ruler into a chunk of clay and secure the clay to the table so that your apparatus will not slip or topple over. Make sure that the end of the ruler is touching the surface of the table. This will ensure that your measurements of the height of the lens will be accurate.

    Optical Apparatus

  7. Now you are ready to measure your objects with your magnifying lens apparatus. First collect items to measure and organize them into a data table. You will need a data table to keep track of your measurements:

    Object Actual Size
    (cm)
    Height of Lens
    (cm)
    Optical Size
    (cm)
           
           
           
           

  8. Now take one of your objects and measure the actual size of the object along the length (if it is a long object) or diameter (if it is a round object like a penny). Write down your measurement in a data table.
  9. Place the object on the table beneath your apparatus.
  10. Adjust your magnifying glass lens to a fixed height above the table using your ruler as a guide by moving the adjustable straw. Write down the height of the lens in your data table.
  11. Now look through the lens of the magnifying glass. Using your taped on ruler as a guide, indicate the size of the object as it appears in the lens. This measurement may or may not match the actual size of the object. Write the optical size measurement in the data table.
  12. Continue to change the height of your magnifying lens, and taking optical measurements of your objects. Remember to write both the height of the lens and measurement of the object in your data table each time.
  13. After collecting your data, it will be helpful to make a graph to help you interpret your data and think about the relationship between the height of the objective and the optical size of each object.

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Variations

  • Magnification is the ratio between the apparent size of an object and its true size. From your graph, you can actually calculate the magnification of your lens by using a formula. A formula is a description of how to use math to calculate something from data you have collected. Here is a simplified formula to calculate the magnification of a lens. Use it to calculate the magnification of the lens in your experiment.

    Magnification =   Apparent Size
    Actual Size

  • Different types of lenses bend light in different ways, which make a big difference to how your eyes will see objects through a lens. Some shapes of lenses will make objects smaller rather than larger, or will cause the object to appear upside down. There are many different shaped lenses, which fall into two main categories: concave or convex. Experiment with different shapes and combinations of lenses to see how they change how an object will appear.

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Ask an Expert

The Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.

Ask an Expert

Related Links

If you like this project, you might enjoy exploring these related careers:

optometrist conducting eye exam

Optometrist

Optometrists are the primary caretakers of our most important sense—vision. They diagnose and detect problems not only with vision, but with the health of the eye and the whole body. Based on their diagnoses, they prescribe glasses, contact lenses, and medications; refer patients to opthamologists for surgery; or develop treatment plans, like vision therapy, to help correct for deficits in depth perception. Their work helps people live better at every stage of life. Read more

Looking for more science fun?

Try one of our science activities for quick, anytime science explorations. The perfect thing to liven up a rainy day, school vacation, or moment of boredom.

Find an Activity