Physics 2- study

Sound

produced by vibrating objects.,

Compression

a region of slightly higher pressure where the air molecules are closer together than usual.

wavelength

is equal to the distance between the centres of two successive compressions.

Ultrasound

high frequency sound, above 20 000 Hz, too high to be heard by humans.

Infrasound

low frequency sound, inaudible to human, although we may feel the very slow vibrations.

Sound waves in different materials

Sound travels quickest through solids.

Sound travels well through liquids.

Sound travels slowest through gases.

echo

reflected sound wave.

Echo eqwuation

speed = distance / time

SPEED

Speed = distance / time.

oscilloscope

device that with a microphone attached can be used to display a sound wave.

amplitude

• height of the wave (measured from the centre of the screen)

frequency

• number of entire waves that appear on the screen

wave

means of transferring energy and information from one point to another without there being any transfer of matter between the two points.

Transverse waves

waves where the direction of vibrations is at 90° to the direction in which the wave travels.

example: water waves

Longitudinal Waves

waves where the vibrations of the particles are along the direction in which the wave travels.

Wavelength

distance between one wave peak and the next wave peak along the path of a wave. metrees

Average Speed

Average Speed = Distance moved / Time taken

Acceleration

Acceleration = Change in Velocity / Time taken

Frequency

number of wave peaks that pass a point in one second, measured in hertz (Hz)

frequency = 1 / time period

Time period

time taken for a source to produce one wave.

time period = 1 / frequency

Wave Equation

speed = frequency x wavelength

Refractie index

refractive index, n= speed of light in a vacuum, c / speed of light in that material, v

Refraction occurs

when a wave changes speed as it passes from one region to another.

angle of incidence

• The angle of the wave approaching the boundary

Angle of reflection

• The angle of the wave leaving the boundary

Reflection occurs

A wave hits a boundary between two media and does not pass through, but instead stays in the original medium

electromagnetic spectrum

continous spectrum of waves which includes the visible spectrum.

velocity

speed in a given direction.