The Electromagnetic Spectrum

- Electromagnetic waves are transverse waves. Their vibrations are changes in electrical & magnetic fields at right angles to the direction of wave travel.

All electromagnetic waves:
- Transfer energy as radiation from the source of the waves to an observer.
- It can travel through a vacuum, such as space.
- Travel at the speed of a vacuum or air.

Electromagnetic waves form a continuous spectrum, including:

RADIO WAVES

Radio waves reflected from the ionosphere.

Uses:
- There are radios, televisions, cellphones, and wireless Bluetooth devices.
- Shorter wavelengths prevent the signal from returning to the transmitter and cause it to bend.

Dangers:
- Exposure to enormous amounts of radio waves can lead to cancer and cell damage in radio beams.
- At shorter wavelengths, the signal does not return to the transmitter and does not bend.

MICROWAVES

Uses:
- Cooking food, communications, satellite communication.
- They penetrate internal goods, absorbed by water molecules in food; microwaves absorbed in the body collide with water, intense sources of microwaves.

Dangers:
The intense sources of microwaves internally heat the body's cells and tissues. The body absorbs microwaves that collide with water, which are intense sources of microwave radiation. The microwaves are conducted/connected to energy and then radiated.

INFRARED WAVES 

Uses:
There are electrical heaters, cookers, security cameras, and thermal imaging cameras.

Dangers:
- The heating effect of IR can cause burns to the skin.
- The hotter the object, the more IR radiation.
- Use insulating material to stop as much 1 R reaching SWIN.

- Night-vision equipment turns IR waves into an electrical signal, which is displayed on a screen as a picture → allows hidden things in the dark to be seen.

VISIBLE LIGHT WAVES:

Uses:
- Photography (Cameras use lens and shutter speed to determine how much light they want to capture), illumination, and fibre optic communication.

Dangers:
- Looking directly at the sun can cause blindness as it damages the retina.

ULTRAVIOLET WAVES 

Uses:

- Energy-efficient lamps and fluorescent lighting, which absorb 99% of UV radiation, are used on bank notes to detect forgeries, kill bacteria, disinfect water, and produce electrically charged ions.

Dangers:

- Tanning or burning of the skin causes damage to skin cells and eyes, which increases the risk of skin cancer as it damages the DNA.

X-RAYS

Uses:

- Internal imaging, producing electrically charged ions, security scanners of food and medical equipment.

Dangers:

- Mutation of genes that can lead to cancer.

GAMMA RAYS

- Kill all microbes to keep them fresh for a longer period of time.

Uses:

The process involves internal imaging, sterilisation, cancer detection, and the production of electrically charged ions.

Dangers:

Mutation of genes that can lead to cancer.