ShareForce, Energy, & Motion - 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 know the journey
of light rays 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 according to the distance from the object as it 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 the 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 or what are 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. A 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 arts of Astronomy. The tool she
learned to use to observe the objects in the sky was a normal, ordinary
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 refract 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 Earth and takes amazing pictures. In 1999, astronauts flew to the space telescope "Hubble" to fix the mirrors. Which 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 them translate this information into an electrical impulse form
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, had his hearing checked.
Doc Moodle knew right away that Cari's grandfather need 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 canal of the ear, 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 a an earthquake"
she exclaimed! She continued. "most earthquakes take place along
cracks in the surface of Earth. There are breaks in Earth that sometimes
slip along these cracks. Earthquakes generate big energy waves that
transfer 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.
Materials:
- Flat piece of wood for base
- L-shaped stand cutout from wood
- String
- Piece of paper
- Pencil
Procedure:
- Attach the L-shaped stand to the base as shown above.
- Tie the string so it hangs down as shown.
- Lay the piece of paper down on the base.
- Attach the pencil to the string so that it touches the paper.
- 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.
Safety concerns: As with all science lab activities, the most important safety rule is to follow all teacher directions.
Analysis:
- Which kind of energy do glasses help focus?
- What does a hearing aid amplify?
- Which form of energy do seismographs sense?
Check your answers by highlighting the box below.
| 1. Light waves, 2. Sound waves, 3. Seismic waves. |
