P5.2 - Electromagnetic Fields Flashcards
what angle do electromagnetic fields oscillate at (relative to the direction of the wave)?
90 degrees
electromagnetic waves all have …….. ………..
the same velocity
What speed do electromagnetic waves travel at? (and what is this the same as)
3 x 10 ^8 m/s
- same as speed of light
name two sources of electromagnetic waves
microwave, sun
what is the equation to calculate the frequency of a wave?
and what is the unit
wave speed
—————
wavelength
(Hz)
State 2 uses of radio waves
- TV signals
- Used to transfer information (ie. between phones and satellites)
State uses of micro waves,3
- to heat up food in the microwave
- communicate with satellites
- WiFi and bluetooth signals
State uses of infrared waves, 4
- Remote controls
- used in optical fibres
- cooks food in oven or grill
- radiator transfers energy to thermal store
State a use of visible light
- morse code in ships
- for photography
State uses of ultraviolet waves, 5
- helps produce vitamin d
- bodily fluids glow in ultraviolet rays (ie. in crime scenes)
- to detect forged bank notes
- sterilises water (kills bacteria)
- can be used for suntans
State uses of X-ray, 3
- used for X-rays
- can kill skin cancer or other skin cells
- used for airport security
State uses of gamma rays, 4
- can kill cancer cells
- can kill bacteria in food
- can kill people
- can find leaks in underground pipes
Are ultraviolet rays dangerous, and if so why?
YES
- can damage DNA in cells (grow very rapidly and cause skin cancer)
- if eyes exposed, cataracts can develop (make corneas cloudy)
Are X-rays dangerous and if so why?
- can damage cells
- can cause cancer
Are gamma rays dangerous and if so why?
- can damage cells in body
- can kill cells in body
State a source of infrared rays
remote controls
Name the group of the electromagnetic spectrum used to kill cancer cells.
gamma rays or x-rays
Describe the nature of an electromagnetic wave
- oscillate at a right angle/90 degrees to the wave’s direction.
- wave pointing up = electric field
- wave pointing sideways = magnetic field
- it is a transverse wave
Suggest a control variable for an experiment investigating various rays of the electromagnetic spectrum
- keep the same intensity of Electromagnetic radiation
Describe why bones show up white on the X-ray film
- Bones absorb X-rays
- photographic film darkens when it absorbs X-rays
- X-rays pass through soft tissues (such as skin and muscle)
When radiographers operate X-ray machines, they stand behind lead screens. The screens absorb X-rays and prevent the operators from being repeatedly exposed to radiation.
Why this is a necessary precaution.
X-rays / gamma rays can damage DNA / are harmful to cells
what kind of waves are electromagnetic waves?
transverse waves
what do electromagnetic waves transfer?
energy from sources to absorbers
state examples of where electromagnetics transfer waves from sources to absorbers
(and describe what happens to the absorbers because of it)
microwave emits electromagnetic waves -> skin absorbs infrared waves
or “ -> food absorbs microwave radiation
- THEY BOTH HEAT UP
what is the relationship between frequency and wavelength across the electromagnetic spectrum
the greater the frequency, the smaller the wavelength
what are our eyes sensitive to?
only visible light, not absorbed by the atmosphere
can electromagnet waves travel through a vacuum?
and why
yes!
- as they are emitted from the sun and travel to the earth through SPACE
- remember space is a vacuum
describe the difference between a longitudinal and transverse wave
- in a longitudinal wave, oscillations occur parallel to the direction of energy transfer
- in a transverse wave, oscillations occur perpendicular to the direction of energy transfer
