The electromagnetic spectrum
The electromagnetic spectrum is a continuous range of The length of a single wave, measured from one wave peak to the next..
The types of radiation that occur in different parts of the spectrum have different uses and dangers - depending on their wavelength and The number of waves produced each second. The unit of frequency is hertz (Hz)..
There are seven members of electromagnetic family.
The order of electromagnetic waves in the spectrum is shown in the table below.
They are arranged in order of decreasing wavelength (and increasing frequency):
| Energy | Frequency | Wavelength | Radiation type | Typical wavelength in m | Typical use |
| Lowest | Lowest | Longest | Radio waves | 1 | Communication such as television and radio, mobile phones, radar, Wi-Fi, Bluetooth. |
| Microwaves | 1 x 10 -2 | Cooking, satellite communication, speed cameras. | |||
| Infrared | 1 x 10-4 | Heat transfer by radiation 鈥 electric heaters, cooking by grilling, also night vision equipment, optical fibre communication, TV remote control, burglar alarms. | |||
| Visible light | 4 x 10-7 to 7 x 10-7 | Seeing, photography, optical fibre communication. | |||
| Ultraviolet | 1 x 10-8 | Suntan, detecting forged bank notes, helps to make vitamin D, hardening some types of dental filling, nightclubs and bowling alleys to make clothes glow. | |||
| X-rays | 1 x 10-10 | Medical images of bones, airport baggage scanners. | |||
| Highest | Highest | Shortest | Gamma radiation | 1 x 10-12 | Killing cancer cells, sterilising medical equipment, killing bacteria to prolong shelf life of fruit. |
| Energy | Lowest |
|---|---|
| Frequency | Lowest |
| Wavelength | Longest |
| Radiation type | Radio waves |
| Typical wavelength in m | 1 |
| Typical use | Communication such as television and radio, mobile phones, radar, Wi-Fi, Bluetooth. |
| Energy | |
|---|---|
| Frequency | |
| Wavelength | |
| Radiation type | Microwaves |
| Typical wavelength in m | 1 x 10 -2 |
| Typical use | Cooking, satellite communication, speed cameras. |
| Energy | |
|---|---|
| Frequency | |
| Wavelength | |
| Radiation type | Infrared |
| Typical wavelength in m | 1 x 10-4 |
| Typical use | Heat transfer by radiation 鈥 electric heaters, cooking by grilling, also night vision equipment, optical fibre communication, TV remote control, burglar alarms. |
| Energy | |
|---|---|
| Frequency | |
| Wavelength | |
| Radiation type | Visible light |
| Typical wavelength in m | 4 x 10-7 to 7 x 10-7 |
| Typical use | Seeing, photography, optical fibre communication. |
| Energy | |
|---|---|
| Frequency | |
| Wavelength | |
| Radiation type | Ultraviolet |
| Typical wavelength in m | 1 x 10-8 |
| Typical use | Suntan, detecting forged bank notes, helps to make vitamin D, hardening some types of dental filling, nightclubs and bowling alleys to make clothes glow. |
| Energy | |
|---|---|
| Frequency | |
| Wavelength | |
| Radiation type | X-rays |
| Typical wavelength in m | 1 x 10-10 |
| Typical use | Medical images of bones, airport baggage scanners. |
| Energy | Highest |
|---|---|
| Frequency | Highest |
| Wavelength | Shortest |
| Radiation type | Gamma radiation |
| Typical wavelength in m | 1 x 10-12 |
| Typical use | Killing cancer cells, sterilising medical equipment, killing bacteria to prolong shelf life of fruit. |
Radio waves have the lowest frequencies and longest wavelengths, while gamma waves have the highest frequencies and shortest wavelengths.
All of these waves travel at the same speed in free space, which is the speed of light or about 300,000,000 m/s (metres per second).