Cp5 - Electro-magnetic waves Flashcards
Are EM Waves longitudinal or transverse?
Transverse
Can EM Waves travel through a vacuum?
yes
What is speed of EM Waves
300 000 000m/s or 3x10^8m/s
What separates EM Waves from each other
Frequency and wave-lenghts
True or False - can our eyes detect all of the EM Spectrum.
False
What part of our bodies can detect visible light
Our eyes
How many EM Waves are there?
There are seven electromagnetic waves
Order EM Waves in lowest frequency to highest frequency
radio waves
micro waves
infrared
visable light
ultra violet (UV)
Xray
Gamma
What are EM Waves made of?
Oscillating electric and magnetic fields
What is the formula for velocity?
Velocity = frequency x wave length
What is the formula for speed?
speed = distance/ time
Gamma Rays:
what is it used for
what are the dangers
uses = for sterilising things
1. food and medical instruments as it kills bacteria
2. medical imaging - treatment and detection of cancer
3. nuclear power, nuclear weapons
dangers =
an cause mutation of genes and damages cells, leading to cancer
radiation
Xrays:
What is it used for
What are the dangers
Uses = to see inside things viewing internal structures of objects and materials including bodies - used
1. in hospitals to take xrays,
2. airport security scanners to detect hidden objects,
Dangers=
Cancer and hair loss
Ultra Voilet (UV)
What is is used for
What are the dangers
Uses =
1. Illumination (fluorescent lights use UV to transmit visible light
2. Seeing finger prints
3. Security pens used to mark property
4. detecting forged bank notes
5. tanning
6. sterilising water
Dangers = skin burns and skin cancer
Visible Light
What is it used for
What are the dangers
Uses =
1.allows us to see things
2. photography
Dangers = damages retina
Infra red
What is it used for
What are the dangers
Use - Increase or Monitor Temperature
1. Thermal Imaging to monitor temperature
2. Infrared sensors in security systems eg burglar alarams
2. sometimes cooking
Dangers = can burn the skin and damage cells because it is hot
Micro waves
What is it used for
What are the dangers
Uses =
1. cooking in microwaves
2. radio astronomy (satalites)
3. mobile calling - communication
Could cause heating of cells in the body and the radiation is absorbed by water
Radio waves
What is it used for
What are the dangers
Uses =
1. radio communicaton
2. broadcasting
Dangers - heating of biological tissue
What are the units for frequency?
hertz (Hz)
What does the wavelength of a wave describe
distance on one point of a wave to the same corresponding point on the wave
What is the standard unites for wave length?
metres
What is a vacum?
empty space with no particles
What do all waves transfer?
energy
Which part of our bodies detect visable light?
Eyes
Which EM wave has the highest frequency?
Gamma
Which EMf has the longest wave length?
radio waves
Which part of the EM spectrum is used in TV controls?
infrared
Which part of the EM spectrum is used for mobile phone communication?
microwaves
Explain why gamma rays are more dangerous to humans than visible light
2 mark question
Gamma rays are ionising so they an cause tissue damage and cancer but visible light isn’t ironising
Gamma rays carry more energy than visible light so their potential for damage is higher
Explain why signals between satellites are usually transmitted as microwaves?
1 mark question
They can pass easily through the Earth’s watery atmosphere without being absorbed
