HOW ORGANISMS SENSE ENERGY
Sensors and Detectors
OBJECTIVE TODAY:
Our objective today will be to answer the
following questions:
What are sensors and detectors?
What are some examples of machines that are
sensors and detectors?
How do organisms sense energy?
How do specific organs sense energy?
What sensors are used in other living things?
SENSORS AND DETECTORS
A
sensor or a detector is a device that responds to a stimulus,
(energy) such as heat, light, chemical or kinetic. It then generates a
signal that can be measured or interpreted.
Humans and all other organisms have sensors that can detect the
energy around them. This ability may be inherent or has become
an adaptation over time.
Detectors are used in physical science to respond to energy
signals and forces. They are not only necessary for living organisms
to survive, but help us use and enhance our senses to energy.
DETECTORS IN SCIENCE
Scientists have invented various types of sensors to detect energy
forms. For example, a smoke detector in your home will set off an
alarm when the energy from smoke or heat reaches its detection
device. The microphone on your tape recorder detects the energy
from sound waves and creates an electric signal that records the
sound. Here are several other examples:
Solar cells and photographic film detect light.
Microphones detect sound.
Thermometers sense the change in heat or temperature.
Pressure gauges detect touch.
Scales detect and measure the effect of gravity.
There are many devices that detect various chemicals and even odors.
A magnetometer detects magnetic fields.
An electric meter detects electricity.
A Geiger counter detects atomic radiation.
Seismograph/Seismometer: tool that measures the amount of ground movement
(kinetic energy) in earthquakes.
HOW ORGANISMS SENSE ENERGY?
Humans and animals can detect various forms of energy through their sensors and
detectors:
Eye detects light energy
Ear detects sound energy
Skin detects both physical pressure and heat energy
Nose detects certain smells due to chemical reactions
Tongue detects other chemical reactions when food
is broken down.
Inner ear detects gravity
Some animals can also detect electrical signals
and magnetic fields.
HOW OUR EYES SENSE LIGHT ENERGY?
Your eyes are at work from the moment
you wake up to the moment you close
them to go to sleep. They take in tons of
information about the world around you
— shapes, colors, movements, and more.
Then they send the information to your
brain for processing so the brain knows
what's going on outside of your body.
 How the eye works:
http://kidshealth.org/kid/htbw/eyesmovie.html
DETECTORS IN SCIENCE THAT HELP US
Glasses: improve our ways in which we sense light energy.
Glasses are used to focus the amount of light that reaches our cornea.
Most vision problems occur when the eye cannot focus the image onto
the retina. Here are a few of the most common problems:
Myopia (nearsightedness) occurs when a distant object looks blurred because the
image comes into focus before it reaches the retina. Myopia can be corrected with
a minus lens, which moves the focus farther back.
Hyperopia (farsightedness) occurs when a close object looks blurred because the
image doesn't come into focus before it gets to the retina. Hyperopia, which can
also occur as we age, can be corrected with a plus lens. Bifocal lenses, which have
a small plus segment, can help a farsighted person read or do close work, such as
sewing.
Astigmatism is caused by a distortion that results in a second focal point. It can
be corrected with a cylinder curve.
Placing the correct type and power of lens in front of the eye will
adjust the focal point to compensate for the eye's inability to focus the
image on the retina.
ORGANISMS AND LIGHT ENERGY
Eagles have eyeballs that are 35mm
(compared to human eye ball that is 24mm)
This allows Eagles of see 2.0 to 3.6 times
better than that of a human.
Falcons can see a 10cm object from a
distance of 1.5 km away.
Flies have 3,000 lenses in each eye. Allowing
it to process much faster than a human’s eye.
HOW OUR EARS SENSE SOUND ENERGY?
Your ears are in charge of collecting
sounds, processing them, and sending sound
signals to your brain. And that's not all —
your ears also help you keep your balance.
So if you bend over to pick up your cat,
you won't fall down — or even worse —
fall on your cat. Meow!
How the ear works:
http://kidshealth.org/kid/htbw/earsmovie.html?tracking=59983_B
DETECTORS IN SCIENCE THAT HELP US
Hearing Aid:
A hearing aid is a small electronic device that you wear in or
behind your ear. It makes some sounds louder so that a person with
hearing loss can listen, communicate, and participate more fully in
daily activities. A hearing aid can help people hear more in both
quiet and noisy situations. However, only about one out of five
people who would benefit from a hearing aid actually uses one.
A hearing aid has three basic parts: a microphone, amplifier,
and speaker. The hearing aid receives sound through a
microphone, which converts the sound waves to electrical signals
and sends them to an amplifier. The amplifier increases the power
of the signals and then sends them to the ear through a speaker.
ORGANISMS AND SOUND ENERGY:
Humans can hear frequencies between 20
and 20,000 Hz.
Elephants hearing range is between 1 and
20,000 Hz. The very low frequency sounds are
in the “infrasound” range. Humans cannot hear
sound in this range.
Dogs can hear sound as high as 40,000 Hz.
Mice can hear frequencies between 1,000
and 100,000 Hz.
SENSING SOUND ENERGY
Echo Location: is the process of
determining the distance and direction
of objects by using sound.
Echolocation is performed by certain
animals to locate food or obstacles in
darkness, such as in caves and in the
ocean. These animals, which include bats,
toothed whales, oilbirds, cave swiftlets,
and shrews, produce sounds and then
listen for echoes. The delay between the
emission of a sound and the arrival of an
echo indicates the distance of an object.
Video:
https://www.youtube.com/watch?v=j2Vo
ouYxtQo
HOW ORGANISMS SENSE OTHER ENERGIES:
 Earthworm’s entire body is covered with
chemoreceptors (taste/chemical receptors)
Bats can detect warmth (thermal energy) of an
animal from about 16cm away.
Cockroach can detect movement (kinetic
energy) as small as 2,000 times the diameter
of a hydrogen atom.
Star-nosed Mole use its fleshy star nose for
hunting. It has 100,000 nerve fibers that run
from star to the brain. This is almost six times
more than the touch receptors in the human
hand.
http://www.animalplanet.com/tvshows/other/videos/fooled-by-nature-starnosed-mole/