Refraction
What is refraction
Refraction is the bending of a wave either sound or light when it enters one medium from
another of different densities.
Simple experiment to prove sound waves can be refracted
The speaker will produce a sound wave and the microphone connected to the oscilloscope which
will show the waves produced. A balloon filled with carbon dioxide gas, will be placed between
both devices and with the balloon we see that the amplitude increases, which means the sound
becomes louder. Since carbon dioxide is denser than the air the speed will increase. The sound
wave is refracted approaching the normal when the wave propagates from the air into the balloon
and away from the normal when moving out from the balloon
Reverberation and Acoustics
Reverberation
A reverberation is a prolonging of a sound which means the sound lasts longer. An example
would be clapping in an empty auditorium which would make the sound last lounger and echo
Acoustics
Acoustics are the properties or qualities of a room or building that determine how well sound is
transmitted or heard in it around different parts. An example would be the strings in musical
instruments such as a violin or guitar.
Noise
Two problems associated with noise
Prolonged exposure to loud noise can affect your hearing and even lead to loss of hearing
Prolonged exposure to loud noise can increase stress levels and affect sleeping
If listening to music at loud levels you can lower the volume, construction workers can wear ear
plugs or ear muffs to prevent excessive noise from dealing with heavy equipment, wearing these
protective equipment can prevent the problems listed above.
What is an ultrasound
An ultrasound is an imaging test which uses soundwaves to create a picture on a screen of
organs, tissues and other structures in the body (in the medical field)
3 uses of ultrasounds
 Ultrasounds can be used to diagnose conditions in the body such as heart, kidney (kidney
stones), liver etc issues. They can be useful here so that the doctors do not have to go
directly into surgery the patient immediately to examine them, they will use the
ultrasound to have a more precise diagnosis

Ultrasounds can be used to study unborn babies (fetus) to study how the fetus is growing
and to see if there are any issues with the developing fetus

Ultrasounds can be used in biopsies which uses sound waves to help locate a lump or
abnormality and remove a tissue sample for examination under a microscope for
cancerous cells It is less invasive than surgical biopsy, leaves little to no scarring and
does not involve exposure to ionizing radiation. The ultrasound is used to help guide the
needle to the tissue to be sampled.
Light
A lunar eclipse is the total or partial disappearance of the moon from earth, it occurs when the
Moon passes directly behind the Earth into its umbra.
When the sun, earth and the moon are in a straight line, the light from the from sun is shining
onto the earth and the moon is behind it casting a shadow onto the moon, the umbra, and casting
outer shadows, the penumbras.
DIAGRAM OF A LUNAR ECLIPSE
A pinhole camera is one that forms an image via a tiny opening and no lens
The image formed is in focus since the rays of light from the object all pass through a single
point at the opening, the image is inverted, real because it can be projected onto a screen and
smaller in size compared to the object.
DIAGRAM OF A PINHOLE CAMERA