WAVES Flashcards
what is wavelength
distance of an entire oscillation
what is amplitude
maximum displacement of a point of a wave from its rest position
what is time period
time it takes for one complete oscillation
what is frequency
number of waves tht pass a fixed place in a given amount of time
what is a transverse wave
oscillation are perpendicular to the direction of energy transfer
give examples of transverse waves
light, radio, waves of water
what are longitudinal waves?
oscillation is parallel to the direction of energy
give examples of longitudinal waves
sound waves and ultrasound waves
what do longitudinal waves
compressions and refractions
how do you calculate frequency
1/t
whats the practical for frequency,wavelength and speed
fill ripple tank with water znd place a vibrating bar inside of it
connect the vibrating bath to a power pack
place a lamp above the ripple tank and a sheet of white paper belkow it
turn on the ripple tank
to find wavelength : measure the distance of 10 wavelengths on the paper and divide it by 10 to find one
freuquency:set a timer and count the number of waves in 10seconds and ivide it by 10 the find the frequceny of one
speed:frequecy x wavelength
how do you measure the speed of sound
attach microphone to oscilloscope
clap once next to microphone
sound will echo off the wall and come back to microphone
uise oscilloscope to measure the time it took the travel
total distance/time
what happenes in the leslie cube practical
leslie cube with 4 different surfaces
fill leslie cube with hot water
point inferred detector at each surface
keep same distance between lelie cube and detector so measurements are repeatable
the results in order from most to least inferred immersion :matt black shiny black white and shiny matallic
what happens when light enters a medium
their speed changes as does their angle as it bends towards the normal
in refraction what happens to frquency
stays constant
how are the angle of refraction and angle of incidence related
angle of refraction is smaller than the angle of incidence
if we dont have a infared detector in the leslie cube practical what should we use and what are the problems with it
use a thermometer with bulb painted black
the problems are that the resolution is lower this is bad because it will not be able to detect large differences between surfaces
What are the 4 sides of a Leslie cube
Matt black
Shiny black
White
Shiny metallic
What happens to a wave as it slows down when it crosses the boundary
Refracted ray will bend to wards the normal
What happens to a wave as it speeds up after crossing the boundary
Refracted away from away from the normal
What happens if a wave travels at the right angle to the boundary along the normal
Change their speed but not direction
What are used for radio waves and why is it suitable and bad for you
Television and radio signals
Travel long distances through air
Longer wavelengths can bend around obstructions to allow detections of signals
Can penetrate the body
What are microwaves used forand why is it suitable and bad for you
Satellite communications and cooking
Pass through atmosphere to reach satellites
Heat food
Penetrate body causing internal heating
What is ir used for and why is it suitable and bad for you
Cameras and heating
All hot objects emit heat
Transfer energy quickly
Damage cells
What is visible light used for
Fibre optic communication
Shorter wave lengths so can carry more information
How is uv used
Energy efficient lights artificial tanning
Chemicals absorb uv and emit light
How do x rays work
Fires x rays at a body
Dense materials absorb the X-rays
Pass through lungs and small intestine (air)but partially pass through heart(flesh)
Then gets recorded by a detector plate
What happens to X-ray images
Images start off white
Only goes black if an area receives radiation
Name two ways to improve the Leslie cube practical
Flasks that are the same shape and size
Sa is the same
Each flask the same distance away from lamp
Intensity of indeed is the same
What are gamma rays bad
Ionising radiation causes cancer
Whole body Irritated by gamma rays
Exposed to gamma rays for longer
Why does using a high melting point metal good for x rays
Electrons causing heating
Increasing temperature
Allow more electrons to collide per second
