5. Light and The Electromagnetic Spectrum Flashcards
What types of waves are electromagnetic (EM) waves?
Transverse
What do electromagnetic waves transfer?
Energy (not matter).
What type of spectrum do electromagnetic waves form?
A continuous spectrum (EM spectrum)
List the order of the EM spectrum in order of increasing frequency and decreasing wavelength
- Radio waves
- Microwaves
- Infrared
- Visible light
- Ultraviolet (UV)
- X-rays
- Gamma rays
What is the highest frequency electromagnetic wave?
Gamma waves
What is the highest energy electromagnetic wave?
Gamma waves
What properties are shared by all electromagnetic waves?
- They are all transverse waves.
- They all travel at the same speed (3 x 10⁸ m/s)
- They can travel through a vacuum.
- Do not need particles to move.
What range of frequencies of EM waves can be detected by the human eye?
400-700 nanometres
How do the speeds of EM radiation differ in a vacuum and in air?
Electromagnetic waves all travel at the same speed in a vacuum and in air.
What can happen when radiation strikes an object?
It can be:
- transmitted
- reflected
- absorbed
What type of waves can be produced by oscillations in an electrical circuit?
Radio waves
How can radio waves create an alternating current in a circuit?
When radio waves are absorbed, it causes electrons in the receiver to oscillate so there is an alternating current of the same frequency as radio waves that are induced in the receiver.
Where do gamma rays originate from?
Gamma rays are created by changes in an atom’s nucleus.
What health effects can ultraviolet waves cause?
- They can cause the skin to age prematurely.
- They are ionising radiation so can increase the risk of developing skin cancer.
What health effects can X-rays and gamma rays cause?
- They are ionising radiation so can cause mutations in genes.
- They can lead to increased risk of developing various cancers.
What health effects can infrared rays cause?
Infrared waves can cause burns to skin/tissue.
How does electromagnetic radiation affect electron arrangement in atoms?
Absorption or emission of electromagnetic radiation can cause electron arrangement to change. (It can remove electrons from the atom or move electrons further from the nucleus).
How do atoms become ions?
By losing an outer electron.
What are the effects of body cells absorbing radiation?
Large amounts can damage cells.
Smaller amounts cause mutation, causing cells to divide rapidly, which can lead to cancer.
List uses of radio waves and explain
- Broadcasting
- Satellite transmissions
- Communications
This is because radio waves have long wavelengths and can travel long distances without losing quality.
State and explain uses of microwaves
- Cooking, as microwaves are absorbed by heat and fat/water foods.
- Communications
- Satellite transmissions
State and explain uses of infrared radiation
- Cooking food, as it transfers thermal energy.
- Electric heaters
- Thermal imaging
- Optical fibres
- Security systems
- TV remote controls
- Short range communications
State and explain uses of visible light
- Illumination
- Vision
- Photography
State and explain uses of UV radiation
- Sterilisation, as it kills bacteria.
- Fluorescent lamps, as it radiates low heat but high energy making it efficient.
- Sun tanning
- Detecting forged bank notes
- Security marking
State and explain uses of X-rays
- Medical imaging and treatment, as x-rays are very high in energy and can easily penetrate body tissues.
- Airport security scanners
- Looking inside objects
State and explain uses of gamma rays
- Medical treatments, such as radiotherapy in the treatment of cancer.
- Sterilising food and medical equipment.
Which waves of the EM spectrum are regarded as most dangerous and why?
Gamma and X-rays because they have the highest energy and frequency.
