The e-m spectrum

Light is part of a continuous electromagnetic spectrum…

1. Radio

2. Microwave

3. Infrared

4. Visible

5. Ultraviolet

6. x-ray

7. Gamma ray (radiations)

all waves in the electromagnetic spectrum travel….

at the same speed in free space

Use of radio waves

broadcasting and communication

Uses of Microwaves

cooking and satellite transmissions

Uses of infrared

heaters and night vision equipment

Uses of visible light

optical fibres and photography

Uses of ultraviolet

• fluorescent lamps.

• sterilisation of medical equipment and water purification.

• security markings for checking bank notes.

Uses of x-rays

observing the internal structure of objects, materials and medical applications.

Uses of gamma rays

• sterilizing food and medical equipment, because gamma rays kill bacteria.

• detect cancerous cells in the body, by using a PET scanner.

Effects of excessive exposure of the human body to electromagnetic waves: Microwaves

internal heating of body tissue

Effects of excessive exposure of the human body to electromagnetic waves: Infrared

burns skin

Effects of excessive exposure of the human body to electromagnetic waves: Ultraviolet

cause skin cancer and blindness

Effects of exposure on the human body. Gamma rays

causes cancer and cell mutation, because radiation is ionising (gamma has the highest energy.)

ways in which you can reduce the risks, when using gamma radiation (eg. a doctor.)

• use gamma radiation for a limited time.

• work at a distance/in another room.

state 2 sections of the EM spectrum that are used for cooking

1. microwaves.

2. infrared.

state 2 differences between ultrasound, and ultraviolet waves

1. ultrasound waves need a medium vs ultraviolet is an electromagnetic wave.

2. ultrasound waves are longitudal vs ultraviolet waves have a much higher frequency.

An ultrasound image is caused by waves which bounce off the fetus. This is an example of waves that are…

reflected

state 2 similarities between visible, infrared, and ultraviolet light

• travel at the same speed when in a vacuum.

• all transverse waves.

properties all waves share in the electromagnetic spectrum

• all transverse waves.

• all travel through free space (a vacuum).

• all travel at the same speed in free space.

lower energy waves have…

• longer wavelengths

• lower frequencies

higher energy waves have…

• shorter wavelengths.

• higher frequencies.

colour: longest wavelength/lowest frequency

red (think: ROGYBIV)

colour: shortest wavelength/highest frequency

violet (think: ROGYBIV)