Sound and light Flashcards
what is sound?
type of energy made by vibrations that travel through the air or another medium as an audible mechanical wave at around the speed of 340 m/s
what is light?
electromagnetic radiation of any wavelength that can travel in a vacuum with a speed of 299,792,458 (m/s) meters (about 186,000 miles) per second.
How does sound travel?
type of energy made by vibrations which create sound waves in the way they travel through mediums.
How does light travel?
light travel in a straight direction through waves, commonly known as light waves
How are sounds produced?
Sounds are made when objects vibrate. The vibration makes the air around the object vibrate and the air vibrations enter your ear.
You hear them as sounds but you cannot see vibrations.
vibration…
object moving in a back and forth way around a point.
sound is made through vibrations
Why do we see lightning before we can hear it?
A person on the ground sees the lightning flash before hearing the thunder because light at a speed of around 300,000,000 meters per second travels much faster than sound which moves at 340 meters per second which therefore allows us to see the lightning before the sound.
what are waves?
waves are a way of transferring energy in which sound travels through waves, known as sound waves.
what is reflection?
a light wave is bounced back by an object/mirror
what is refraction?
When light changes direction passing from one material to another due to a change in density.
refraction = “break” of light
what is the law of reflection?
The law of reflection states that: angle of incidence i = angle of reflection r.
For example, if a light ray hits a surface with an angle of incidence of 45°, it will be reflected with an angle of reflection of 45°.
what is the law of refraction?
When light travels from air into glass it slows down because glass is more (optically) dense than air.
This change in speed can cause the light to bend at the boundary between the two transparent materials.
The change in direction of a beam of light as it travels from one material to another is called refraction.
The normal is a construction line drawn at right angles to the surface of the glass block.
Glass is denser than air, so when light passes from air into glass it slows down.
If the ray meets the boundary at an angle to the normal, it bends towards the normal.
Light speeds up as it passes from glass into air because air is less dense than glass.
If the ray meets the boundary at an angle to the normal, it bends away from the normal.
The greater the change of speed of light at a boundary, the greater the refraction.
Light is bent more by glass than by water because glass is denser than water and so slows it down more.
what is white light?
a combination of all colours in the colour spectrum. It has all the colours of the rainbow.
Combining primary colours of light like red, blue, and green creates secondary colours: yellow, cyan, and magenta.
All other colours can be broken down into different combinations of the three primary colours.
dispersion…
separation of colours
can be done through a glass prism
how can we see colour?
The color of light coming from an object is what gives it color. Light travels into the eye to the retina located on the back of the eye. The retina is covered with millions of light sensitive cells called rods and cones. When these cells detect light, they send signals to the brain.
what is a ray diagram?
shows how light travels, including what happens when it reaches a surface.
In a ray diagram, you draw each ray as:
a straight line;
with an arrowhead pointing in the direction that the light travels.
