P13 - EM Spectrum & Waves Flashcards
What are Carrier waves?
Waves used to carry any type of signal
What is a charge-coupled device (CCD)?
An electronic device that creates an electronic signal from an optical image formed on the CCD’s array of pixels
What is a contrast medium?
An X-ray absorbing substance used to fill a body organ so the organ can be seen on a radiograph
What is the electromagnetic spectrum?
The continuous spectrum of electromagnetic waves
What is ionisiation?
The process by which atoms become charged
What are microwaves?
Electromagnetic waves between infrared radiation and radio waves in the electromagnetic spectrum
What is an optical fibre?
Thin glass fibre used to transmit light signals
What is a radiation dose?
Amount of ionising radiation that a person receives
What is a radiowave?
Electromagnetic waves of wavelengths greater than
0.1 m
What is Ultraviolet Radiations (UV)?
electromagnetic waves between visible light and X-rays in the electromagnetic spectrum
What is wave speed?
The distance travelled per second by a wave crest or trough
What is white light?
Light that includes all colours of the spectrum
What is the structure of an electromagnetic wave?
- Electromagnetic waves are transverse waves that transfer energy.
- Vibrations are electric and magnetic fields forming the EM wave.
- Electric and magnetic fields oscillate 90° to wave direction and to each other.
What are the properties of an electromagnetic wave?
• They are transverse waves.
• They can travel through a vacuum (they do not require a medium to travel through).
• They travel at the speed of light
• EM waves with a high frequency have high energy, while low frequency waves have low energy
• They form a continuous spectrum
What is an electromagnetic wave?
Electrical and magnetic disturbances that transfer energy from one place to another
What is the order of the EM spectrum (from long wavelength to short) (low frequency to high)
-Radio Waves = LOW
-Microwaves
-Infrared
-Visible Light
-Ultraviolet Light
-X-rays
-Gamma radiation = HIGH
What is the speed of light in a vacuum?
3.0×10^8m/s
What is the equation for the speed of a wave?
Wave speed = Frequency x wavelength
If a shiny white can of water and a matt black can of water are both heated by an infrared lamp, which will heat quickest?
- Black beaker water temperature increases more than white beaker water.
- Matt, dark surfaces absorb more infrared radiation.
- Shiny, light surfaces absorb less infrared radiation.
What emits more infrared radiation, a shiny white surface or a matt black surface?
- Matt black surfaces: good emitters of infrared radiation
- Dark matt surfaces: excellent emitters of infrared radiation
- White shiny surfaces: poor emitters of infrared radiation
If a matt black can and a white shiny can where both filled with hot water, which volume of water would be hottest after 5 minutes?
- Shiny white can = hottest water
- Shiny white = poor infrared emitter
What are the properties of a short wavelength carrier wave?
• More information carried
• More energy carried
• Shorter range (greater absorption by the atmosphere)
• The less they spread out
What are the properties of a long wavelength carrier wave?
• Less information carried
• Less energy carried
• Greater range (less absorption by the atmosphere)
• The more they spread out
What can Ultraviolet light be used for?
• Sun beds
• Fluorescent materials
• Security
• Sterilisation
How can Ultraviolet light be used with fluorescent materials?
- Fluorescent materials absorb UV light and re-emit it as visible light.
- Used in fluorescent paint.
- Applied in fluorescent light bulbs (highly energy-efficient).
How can UV light be used in security?
Some types of ink are invisible until UV light is shined on it. They absorb the UV light and re-emit it as visible light. This can be used to mark valuable objects or money
How can UV light be used in sterilisation?
UV light destroys microorganisms
What are the 3 types of ionising radiation?
• UV Light
• X-rays
• Gamma radiation
What are the dangers of UV light?
- Harmful to human eyes, can cause blindness
- Harmful to skin: premature aging, sunburn
- Can cause skin cancer as it is ionizing
How can you protect yourself from the dangers of UV light?
- Use skin creams to block UV waves when staying outdoors in summer.
- Avoid looking directly at the sun or other UV light sources.
- Limit tanning bed use to the recommended time and wear protective goggles.
How are X-rays produced?
X-rays are produced when electrons or other particles travelling at high speeds are stopped. X-ray tubes are used to produce X-rays
How are gamma rays produced?
Gamma rays are produced when unstable nuclei in radioactive substances decay and release energy in the form of EM waves
What are some similarities of X-rays and Gamma Rays?
• Very high frequency
• Very low wavelength
• High penetrating power
• Will be stopped by a thick lead plate
Describe the penetrating power of Gamma rays and X-rays
- Gamma rays and X-rays are highly penetrating due to short wavelengths.
- Short wavelengths mean they carry more energy than longer wavelength EM waves.
- Gamma rays have shorter wavelengths than X-rays.
- Gamma rays are more strongly penetrating than X-rays.