Electromagnetic waves and refraction Flashcards
(20 cards)
Order of waves based on wavelength, biggest to smallest
-radio waves
-micro waves
-infra red
-visible light
-ultra violet
-x rays
-gamma rays
What kind of waves are electromagnetic waves
Transverse waves
What area EM waves generated by
-a variety of changes in atoms and their nuclei
Do all EM waves travel at the same speed through air an a vacuum
Yes
Why can EM waves travel through a vacuum
-because they aren’t v… of p…, they are vibrations of e… and magnetic f…
-because they aren’t vibrations of particles, they are vibrations of electric and magnetic fields
What happens when a wave crosses a boundary at an angle and changes direction
It is refracted
What happens when a wave is refracted
-a wave crosses a boundary between materials at an angle and changes direction
If a wave crosses a boundary and slows down will it bend towards or away from the normal
Towards
If a wave crosses a boundary and speeds up will it bend towards or away from the normal
Away from
If a wave enters a denser material will the waves bend towards or away from the normal
Towards
If a material enters a less dense material will it bend towards or away from the normal
Away from
What is the optical density of a material
A measure of how quickly light can travel through it
-the higher the optical density the slower the light travels through it
What will happens if a wave is travelling along the normal
It will change speed, but isn’t refracted
Investigating refraction
- Place a t… rectangular b… on a piece of p… and t… around it
- Turn off the l… and use a r… box to shine a ray of l… at the m… of one of the s… of the block, then t… the i… ray, and mark where it e… from the b…
- R… the block and j… up the point where the light e… and l… the box using a r…, this shows the r… ray
- Draw the n… at the point where the l… ray e… the block
- use a p… to measure the angle between the i… ray and the normal (angle of i…), and the angle between the r… ray and the n… (angle of r…)
- R… this experiment using b… made of different m…, keeping the i… angle the same
- Place a transparent rectangular block on a piece of paper and trace around it
- Turn off the light and use a ray box to shine a ray of light at the middle of one of the sides of the block, then trace the incident ray, and mark where it emerges from the block
- Remove the block and join up the point where the light entered and left the box using a ruler, this shows the refracted ray
- Draw the normal at the point where the light ray entered the block
- use a protractor to measure the angle between the incident ray and the normal (angle of incidence), and the angle between the refracted ray and the normal (angle of refraction)
- Repeat this experiment using blocks made of different materials, keeping the incident angle the same
What are electromagnetic waves made up of
Oscillating electric and magnetic fields
What are alternating currents (ac) made up of
Oscillating charges
The frequency the waves produce is equal to what
The frequency of the alternating current
How can u produce radio waves
-using an alternating currents in an electrical circuit
What is a transmitter
-the object in which the charges (electrons) oscillate to create a radio wave
How are radio waves detected
-when the waves reach a r… the radio w… are a…
-the energy carried by the w… is transferred to the e… in the material of the r…
-this energy causes the e… to o…, generating an a… current
-this c… has the same f… as the radio w… that g… it
-when the waves reach a receiver the radio waves are absorbed
-the energy carried by the waves is transferred to the electrons in the material of the receiver
-this energy causes the electrons to oscillate, generating an alternating current
-this current has the same frequency as the radio wave that generated it
