What relationship do wavelength and frequency have to wave energy?
Increasing frequency (the same as decreasing wavelength) = Increasing energy
Which EM wave has the least energy?
Radio
Which EM wave has the most energy?
Gamma rays
What is a good mnemonic for remembering the EM spectrum?
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What is the order of the EM spectrum, from least to most energy?
Radio Microwaves Infrared Visible Light Ultraviolet Radiation X-Rays Gamma Radiation
Which EM wave has the shortest wavelength?
Gamma Rays
Which EM wave has the largest wavelength?
Radio
What is the speed of EM waves?
ALL EM waves travel at 300 million m/s through a vacuum.
What are the uses of radio waves?
- TV
- Radio
- Mobile Signals
- Bluetooth
What are the uses of microwaves?
- Communications (e.g. Satellite TV)
* Mobile phone signals
What are the uses of infrared?
- Optical fibres (communication)
- Remote controls (TVs)
- Infrared scanners (medicine)
- Infrared cameras
The shorter the wavelength of a radio wave…
- The more information it can carry
- The shorter the range (because it is absorbed by the atmosphere)
- The less it spreads out (by diffraction)
What are different wavelengths of radio waves used for?
- Microwaves - Satellite phone (can travel through the atmosphere)
- Less than 1m - TV (can carry a lot of information)
- 1 - 100m - Local radio stations (limited range)
- More than 100m - International radio stations (long range)
What are optical fibres?
Very thin transparent wires that are used to transmit signals by light and infrared radiation.
What are the uses of ultraviolet radiation?
- Sunbeds
- Security pens
- Fluorescent lights
What are the uses of X-Rays?
- X-Ray pictures of broken bones
- Tumour therapy
- CT scanners
What are the uses of gamma radiation?
- Killing bacteria in food
- Sterilising surgical instruments
- Killing cancer cells
What are the hazards of microwaves?
Can cause heating of internal body tissue.
What are the hazards of infrared?
Can cause burns.
What are the hazards of x-rays and gamma rays?
Can ionise cells, which can kill or damage the cell. Lower doses can cause cell mutation and cancer.
