Electromagnetic Radiation Flashcards
Where in our lives do we use electromagnetic radiation
Broadcasts from tv stations, radio stations and orbiting satellites. Microwave ovens, a remote control to open a garage door, cell phones etc
What are water waves, waves in a string or spring and sound waves called
Mechanical waves
What do mechanical waves require that electromagnetic radiation does not require
A propagation medium
Why doesn’t electromagnetic radiation need a propagation medium
They propagate in an empty space
Why does electromagnetic radiation have a dual nature
It acts a wave and a particle
What is diffraction
The ending or spreading of waves around the edge of a barrier or opening
What is the photoelectric effect
It is an effect that showcases that light, and all electromagnetic radiation has particle properties
What is a photon
A particle of light. It is an energy packet of light
What is the source of electro magnetic radiation
The acceleration of electrical charges. Electric charges in motion cause a change in magnetic field
What is a changed magnetic field always accompanied by
A changed electric field That is perpendicular to the direction of the magnetic field
What are electromagnetic waves
Varying electrical and magnetic fields propagated in the form of waves
What are the seven main groups in the electromagnetic spectrum (in order)
Radio waves, micro waves, infrared, visible light (ROYGBIV), ultra violet, x-rays, gamma rays
What are the properties of electromagnetic waves
- they are transverse waves
- they move the same speed in a vacuum (3 x 10^-8 m.s^-1)
- can move through a vacuum (don’t need a medium to propagate through)
- they can move through mediums but it will move slower than in a vacuum
- transfers energy from one place to another (when charges accelerate they radiate energy)
- they undergo diffraction and interference
What are examples of radio waves
Radio, tv broadcasts, communication
What are the main sources of radio waves
Transmitting antenna as in radio and tv stations
What are the uses of micro waves
- Micro wave ovens (they carry the energy to water molecules in food and heats it)
- radar air control to determine the position of an aircraft
- satellite communication
What is the main source of microwaves
Klystron
What are the uses of infrared waves
- transfers energy or heat and gives us a feeling of warmth in our skins when we stand in front of a heater
- used in thermal cameras
- remote controls
- navigation
What are the main sources infrared
Warm bodies like fires, sun
What are the uses of visible light
- production of food by plants
-to enable us to see things around us
What are the main sources of visible light
Sun, globes
What are the uses of UV rays
-lighting
-optical illumination
- fluorescent pen (highlighter)
-detect forged bank notes
- bees use it because flowers stand out more at this frequency
What are the main sources of UV rays
Sun, florescent lamps
What are the main uses of X-rays
-medical imaging
-CT-scan
- security checks
