Waves Flashcards
What do waves transfer
Energy but no matter
What is the difference between electromagnetic waves and mechanical waves
Electromagnetic waves: can travel through anything, including vacuums(e.g. space). Travel at the speed of light: 300,000 000 m/s
Mechanical waves: need material to travel brought, cannot travel through a vacuum
What is the difference between longitudinal waves and transverse waves
Transverse waves: energy travels perpendicular to the wave length, only go up and down or side to side
Longitudinal waves: energy travels in the same direction as the wave
What is amplitude
Height of wave or depth of a trough
What is the definition of frequency and how’s it measured
The number of waves present passing one point, hertz (Hz)
Define period
The time needed for one complete cycle of vibration to pad in a given point
Define wavelength
The distance on a wave between two crests and troughs
Define speed
Ten distance travelled in one unit of time
Define compression
Molecules moving closer together in a sound wave
Define rarefaction
Molecules moving further away in a sound wave
Name the electromagnetic spectrum in order
Lowest frequency (longest wavelength)to highest frequency (shortest wavelength): Radio + tv waves Microwaves Infrared Visible Ultraviolet X-rays Gamma rays
Describe the properties, application and the hazards of a radio wave
There are no hazards
Used in TV, telephone, WIFI, Radar
Radiated energy
Can be reflected, refracted and detracted
Describe the properties, application and the hazards of microwaves
Travel in straight line Flow through thin outer layer of cable Used in wireless communications Used for heating; communications Can heat body tissue like it heats food Unsure long term effect
Describe the properties, application and the hazards of infrared waves
Can produce changes in lens in eye Treat skin diseases Relieve muscle pain Used in wireless communications Night vision
Describe the properties, application and the hazards of visible light waves
Can see from the human eye
Refract when passing from one material to another
Red, orange, yellow, green, blue, indigo, violet
Can burn retina or even the skin (lasers)
Describe the properties, application and the hazards of ultraviolet waves
High energy Penetrate skin Sunburn or even skin cancer Used to disinfect medical equipment Purify liquids Damage eyesight
Describe the properties, application and the hazards of x-rays
Travels in straight lines Have a high penetrating power Electrically neutral Used for medical purposes Radiation exposure can cause cell mutations or even cancer
Describe the properties, application and the hazards of gamma rays
Has no mass Has no charge Travel at speed of light Used for killing cancer cells Making pictures in brain Sterilising equipment Cause sickness or even death
What travels in straight lines
Light in waves
Define refraction
When light travels to a more dense object the light refracts
Describe a diverging lens
Otherwise known as a concave lens, it gets smaller in the middle and fatter the further up u go. It helps long sited people see properly. It helps make sure that the focal sight lines up with the back of the retina
Describe a converging lens
Otherwise known as convex lens, it has the shape of a an eye (wider in the middle skinnier at the edges). Helps short sited people. It helps make the focal point of the eye line up with the retina.
What is formed when white light refracts through a prism
A spectrum
Describe how the lens change shape to focus light onto the retina
Ciliary muscles and ligaments contract, the lens thins or thickens and is focused on the retina
How do you calculate weight on a planet
Weight= mass x g
G is gravitational field strength measure in N/kg
How do lenses change to correct long and short sited people
the lens changes shape so that the focal point is on the retina
For short sited u would need a convex lens
For long sited u would need a concave lens
When are sound waves produced
When an object vibrates
Are sound waves longitudinal or transverse, explain sound waves
Longitudinal, they travel through the air as a series of compressions and rarefaction.
It can travel through solids, liquids and gassed but not through vacuums
What state does light travel in
Straight lines called waves
