The Electromagnetic Spectrum

Key Issues

Titles

Chapters

• All types of electromagnetic waves travel at the same speed through a vacuum (space)
• Alternating Currents
• Analogue and Digital
• Analogue and digital signals
• be able to describe the importance of carrying information over short and long distances by: infrared - remote controls and thermal imaging
• be able to describe the importance of carrying information over short and long distances by: microwaves - mobile phones
• be able to describe the importance of carrying information over short and long distances by: radio waves - radio and TV
• be able to describe the importance of carrying information over short and long distances by: visible - fibre optics
• be able to state one use in communication systems: infra-red - remote controls and thermal imaging
• be able to state one use in communication systems: microwaves - mobile phones
• be able to state one use in communication systems: radio waves - radio and TV
• be able to state one use in communication systems: visible - fibre optics
• Communication signals may be analogue (continuously varying) or digital (discrete values only, generally on and off). Digital signals are less prone to interference than analogue and can be easily processed by computers
• Dangers of excessive exposure to certain electromagnetic waves
• describe some uses and dangers of microwaves, infrared and ultraviolet waves in domestic situations
• describe some uses of radiowaves, microwaves, infra red and visible light in communication
• describe some uses of X-rays and gamma-rays in medicine. (Excluding detection of various regions of the spectrum)
• describe, in terms of wavelength and frequency the differences between the regions of the electromagnetic spectrum
• Differences in Wavelength
• Different wavelengths of electromagnetic radiation are reflected, absorbed or transmitted differently by different substances and types of surface
• Different wavelengths of electromagnetic radiation have different effects on living cells
• Effects on Living Cells
• Electromagnetic Radiation
• Electromagnetic radiation travels as waves and moves energy from one place to another
• Electromagnetic waves obey the wave formula: wave speed (metre/second, m/s) = frequency (hertz, Hz) × wavelength (metre, m)
• Harmful effects of electromagnetic radiations
• identify the regions of the electromagnetic spectrum
• Infra red and visible light can be used to send signals along optical fibres and so travel in curved paths
• Infra-Red
• know a definition for frequency and wavelength
• know that electromagnetic radiation travels as waves
• lasers emit signals that can carry information through optical fibres and how leakage of light is prevented by total internal reflection
• Light waves are transverse waves which can be reflected, refracted and diffracted
• Light, radiowaves, microwaves, infra red rays, UV rays, X-rays and gamma rays as part of the electromagnetic spectrum
• Microwaves
• Microwaves can pass through the Earth's atmosphere and are used to send information to and from satellites and within mobile phone networks
• Radio waves, microwaves, infra red and visible light can be used for communication
• recall that the electromagnetic spectrum includes radio waves, microwaves, infrared, visible light ultraviolet waves, X-rays and gamma-rays and be able to arrange them in order of wavelength
• Some radiations mostly pass through soft tissue without being absorbed, some produce heat, some may cause cancerous changes and some may kill cells
• THE CHARACTERISTICS OF WAVES
• THE ELECTRO-MAGNETIC SPECTRUM
• The electromagnetic spectrum is continuous but the wavelengths within it can be grouped into types of increasing wavelength and decreasing frequency: gamma rays
• The electromagnetic spectrum is continuous but the wavelengths within it can be grouped into types of increasing wavelength and decreasing frequency: infra red rays
• The electromagnetic spectrum is continuous but the wavelengths within it can be grouped into types of increasing wavelength and decreasing frequency: microwaves
• The electromagnetic spectrum is continuous but the wavelengths within it can be grouped into types of increasing wavelength and decreasing frequency: radio waves
• The electromagnetic spectrum is continuous but the wavelengths within it can be grouped into types of increasing wavelength and decreasing frequency: ultraviolet rays
• The electromagnetic spectrum is continuous but the wavelengths within it can be grouped into types of increasing wavelength and decreasing frequency: visible light
• The electromagnetic spectrum is continuous but the wavelengths within it can be grouped into types of increasing wavelength and decreasing frequency: X-rays
• The uses and the hazards associated with the use of each type of radiation in the electromagnetic spectrum
• The uses of electromagnetic radiations
• The Wave Formula
• These effects depend on the type of radiation and the size of the dose
• Total internal reflection - optical fibres and prisms
• Types of Electromagnetic Radiation
• understand how infra-red can be monitored using special detectors and is used in forensic science, night sights and burglar alarms
• Uses and Hazards of Radiation
• Uses of electromagnetic radiations
• Using Waves for Communication
• When radiation is absorbed the energy it carries makes the substance which absorbs it hotter and may create an alternating current with the same frequency as the radiation itself