22/05/09
Amplitud
La amplitud de una onda de sonido es el grado de movimiento de las moléculas de aire en la onda, que corresponde a la intensidad del enrarecimiento y compresión que la acompañan. Cuanto mayor es la amplitud de la onda, más intensamente golpean las moléculas el tímpano y más fuerte es el sonido percibido.

Intensidad
La intensidad fisiológica o sensación sonora de un sonido se mide en decibelios (dB). Por ejemplo, el umbral de la audición está en 0 dB, la intensidad fisiológica de un susurro corresponde a unos 10 dB y el ruido de las olas en la costa a unos 40 dB. La escala de sensación sonora es logarítmica, lo que significa que un aumento de 10 dB corresponde a una intensidad 10 veces mayor: por ejemplo, el ruido de las olas en la costa es 1.000 veces más intenso que un susurro, lo que equivale a un aumento de 30 dB.

Sound:
Is a traveling wave which is an osilation of pressure through a solid liquid or gas.
Perception: for humans, hearing is normally limited to the frecuessies between about 12 Hz and 20.000 Hz although this limits are not defined.

Homework:
-physics of sound
-longituditional and transversal waves
-sound waves properties
-speed of sound

light
No one can see anything in a completely darkned room. There has to be
Light before you can see. You see when light enters you eye. And so you have to know something about light to understand how the eyes work.

What is light?
Light is a kind of energy .it’s a type of radiation. Light energy is given off by the sun, by candles, and other light sources.
Light energy travels from one place to another. The light travels in straight lines (you can see that from the pictures of the sun) it’s often useful to think of the light travelling through the air at 300.000 km each second.






Shadows and reflexions:
Because light travels in straight lines, shadows form.

What’s a shadow?
Is an area behind an object where no light from a light source reaches.
When the sun shines on a object like a tree, the sun’s rays cannot bend round corners to reach the area behind it. That’s why that
The area behind it. That’s why the area behind the tree is dark, and that’s what make
The shadous.
Light rays can be bounced off or reflected of and object. You see this board because rays of light are being reflected from it in to your eye shiny surface, like mirrors reflect light you can see how a mirror reflect to the rays.
Class work:
-investigate
1. What is a light source? Give some examples
2. Write two facts about light rays.
A. a shadow
B. reflecting light?
4. Why does a shadow form behind you when the sun shines?
5. Mirrors and polished cars reflect light well. Walls don’t why not?
6. Try to find out: does the moon give off light or reflect it?
Development
1) Lantern, phosphors, lamp bulb landle.
2) A) That your rays to direct.
b) To produce shadow.
3) Shadow. Is where not reflect the the light,
-reflecting light. Produce shadow.
4) Because the light no reflec my.
straigh line

5)Because the mirrors have shiny.

6)NO, the moon is a satellite it does not possess their own light, the light of the moon we see q is the reflection of sunlight on its surface, so depending on where we see that sometimes the full, half rising etc, and that happens light when it is blocked from the sun ...

Coathanger Gong

You will need:
- 1 Coathanger
- 2 Pieces of 30cm String


Instructions
1. Tie the strings to the corners of the coathanger.
2. Hold the string in your hands so the coathanger dangles downward.
3. Gently knock the coathanger on a hard surface - is the sound loud or soft?
4. Wrap your fingers around each string and place your fingers in your ears.
5. Repeat the experiment with your fingers in your ear. Does the sound get louder or softer? Why?

Light and sound
Light: The light comes from the sun. It is quite high up in the sky because the shadwos are long ( vertical plane )Other sources of light are: the moon, lamp, candles, torches, screens, and so on.Natural sources of light: the sun and the moon.The shope and the size of the shadow depends on the shope of the object that is causing the shodow and its orientation with respect to the sources of lightSound: Intense sounds can be heard from a greater distance from the place of origin then weaker sounds. For example: The sounds made by a computer can be heard when we are working on the computer but not if we are 40 or 50nmeters away.The pitch is defferent Alson, much more intense sounds are made on a drum thet on guitar.