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Devices to Perceive Energy

Cari and the eyeballs of light. Have you ever wondered why Cari Taughter needs glasses? Well, first you will need to understand how light rays travel though the eye into the brain. So, hold on to your myopia; here we go! As the light passes through the cornea, the shape of the eyeball will determine the focus of the image. Throw a ball to a friend. Notice the change of focus your eye automatically makes. That is because the light, after going through the cornea, will pass through a lens that changes shape as the distance from the object increases or decreases. Then, the lens refracts the light (or does a loopty lou), projecting an inverted (upside down) image on the retina. The last part of the light's journey takes us to the retina. The retina is a complex layer of cells on the back of the eyeball. The retina has little objects called cones and rods. Any one hungry?? Think of ice cream cones, and candy bars. The rod is for light and cone is for color. These generate small nerve signals when they are hit by light. These signals are carried to the brain by the optic nerve.
So ... why does Cari Taughter need glasses? Well, her eyeball has become misshaped and is now too long. The image forms in front of the retina, therefore, she needs corrective lenses called eye glasses. The type of lens she would need would be a concave lens. Her condition is myopia, which is commonly known as near-sightedness. Now, if her eye was too short, she would need a convex lens, for the condition known as hyperopic or far-sightedness. Do you wear glasses? What type of lens do you wear? The strength of a lens is determined by the lens material and the angle of its curve.

Cari views the Stars

Cari was an amazing student in the science of Astronomy. The tool she learned to use to observe the objects in the sky was a normal telescope. The telescope is an instrument that collects visible light, a small fraction of the electromagnetic spectrum. It forms enlarged images of distant objects and concentrates them through an eye-piece for better observation. The simplest optical telescope is made with two lenses. One lens, called the objective lens, collects light and forms an image at the back of the telescope. The bigger the objective lens, the more light the telescope can gather. The second lens is located in the eyepiece of the telescope. This lens magnifies the image produced by the objective lens. Different eyepieces can be selected depending on the magnification of light that is desired. The light gathered by telescopes on Earth is affected by its atmosphere. Sometimes Cari will fly to the top of the atmosphere to get a better picture.

There are two types of telescopes. Reflecting telescopes use a large, concave mirror to collect light. This is the type of telescope that Cari likes to use! The small mirror inside the telescope reflects the image to the eyepiece lens.



The refracting telescope consists of two convex lenses. The objective lens at the top of the telescope collects light and refracts it to a point at the end of the telescope and the eyepiece lens enlarges the image so it can be seen more clearly.

The Hubble Space telescope is amazing. It orbits the Earth and takes amazing pictures. In 1999, astronauts flew to the space telescope "Hubble" to fix the mirrors. What type of telescope is the Hubble? To learn more about the Hubble Space Telescope visit http://hubble.nasa.gov.

Cari and her grandfather's hearing aids!

One day, Cari noticed that her grandfather couldn't hear! Since she was an excellent student and knew how the ear worked, she knew that her grandfather needed a device to help him hear better. Did you know that ears are extraordinary organs? They pick up all the sound around you and then translate this information into an electrical impulse from your brain to understand. For some people like Cari's grandfather, hearing loss is a problem. Cari knew that casting a spell on her grandfather would not be as useful as getting a hearing aid. She took him to Doctor Moodle, the audiologist,  to have his hearing checked. Doc Moodle knew right away that Cari's grandfather needed help, so he fitted him with his own hearing aid. This device was developed to be used by people that have hearing problems. Have you seen people with hearing aids in their ears? How do they work? A hearing aid is a small, electronic device that amplifies sound. It can fit nicely in the ear canal, or some can be placed behind the ear and vibrate the bones that are inside the ear.


How do hearing aids work? All hearing aids have the same components: a microphone, an amplifier, a receiver and a battery. The parts of the hearing aid work together to amplify sound energy. The microphone changes sound waves into electrical signals. These signals pass through the amplifier of the hearing aid and are made louder. The amplified electrical signals are changed back into sound waves by the receiver and are channeled into the ear.

Have you ever had your hearing checked? How would you know if you need a hearing aid?


Cari's Earth shaking tool- the "seismograph."

One day while Cari was walking to school, she felt the ground shake. When she got to school, Madam Geo was prepared to tell the class why they felt the ground move. "You have just experienced an earthquake" she exclaimed! She continued, "Most earthquakes take place along cracks in the surface of Earth. There are breaks in the Earth that sometimes slip along these cracks. Earthquakes generate big energy waves that transfer energy through the Earth. These waves are called seismic waves. People who are close enough to an earthquake can feel that motion depending upon the amount of energy that is released. That is what you felt this morning!"

She had a device in front of her that engineers developed to measure the shaking of Earth. It is called a Seismograph. A seismograph is able to sense and measure seismic waves. Seismographs have greatly advanced the science of earthquake study. We even used this instrument on the moon to measure moon quakes. Seismographs use an ink pen to record movements of the Earth’s surface. The resulting record is called a seismogram.


Build your own simple seismograph.


  • Flat piece of wood for base
  • L-shaped stand cutout from wood
  • String
  • Piece of paper
  • Pencil
Safety concerns: As with all science lab activities, the most important safety rule is to follow all teacher directions.


  1. Attach the L-shaped stand to the base as shown above.
  2. Tie the string so it hangs down as shown.
  3. Lay the piece of paper down on the base.
  4. Attach the pencil to the string so that it touches the paper.
  5. Create your own earthquake! (Get some friends together and see how hard you can jump up and down! Did you move the pencil? (Hint: if you all jump together it might help.)
A common question asked by people is "How strong was the earthquake?" In order to measure earthquake strength, scientists use the Richter scale. It is named after Charles Richter who developed the scale in the 1930s. The Richter scale measures the amount of energy released by an earthquake.


  1. What kind of energy do glasses help focus?
  2. What does a hearing aid amplify?
  3. What form of energy do seismographs sense?
Check your answers by highlighting the box below.
1. Light waves, 2. Sound waves, 3. Seismic waves.
Congratulations, you have reached the final page for Eighth Grade Integrated Science. If you feel a need to review any area, click one of the heading links below.

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Teachers should view the Teacher Site Map to relate Sci-ber text and the USOE 8th grade science core.

Updated October 24, 2008 by: Glen Westbroek

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