Wave behaviour and electromagnetic waves

Question 1

When a wave meets a boundary between two material, what are the 3 things can that occur ?

Answer 1

1) The wave is absorbed by the second material - wave transfers energy to material energy store, often thermal energy store which leads to heating

2) Wave is transmitted through the second material - waves carry on travelling through new material, often leads to refraction, can be used in communications and lenses of glasses and camera

3) Wave is reflected, incoming ray is neither absorbed or transmitted but sent back away from second material . This is how echo’s are created

What actually happens depends on wavelength of the wave and the properties of the materials involved

Question 2

Are electromagnetic waves longitudinal or transverse and how do they transfer energy ?

Answer 2

Transverse, Oscillations are perpendicular to the direction of energy transfer

Transfer energy from source to an absorber

Question 3

Speed of EM waves

Answer 3

same speed through air or vacuum .
Travel at different speeds in different materials

Question 4

What allows EM waves to travel through vacuum ?

Answer 4

they aren’t vibrations of particles, they are vibrations of electric and magnetic field

Question 5

Wavelength of EM waves

Answer 5

from 10^-15 to 10^4 m
grouped based on their wavelength and frequency = continuous spectrum, only ones our eyes can detect is visible light

Question 6

Spectrum from long wavelength and low freq to short wavelength high freq

Answer 6

Radio waves 1m - 10^4
Micro waves 10^-2 m
Infra red 10^-5m
Visible light 10^-7 m
ultra violet 10^-8 m
X-RAYS 10^-10 m
Gamma rays 10^-15

Question 7

Why is there such a large range of frequencies ?

Answer 7

EM waves generated by variety of changes in atoms and nuclei
This explains why atoms absorb range of freq - each one cause a different change
Because of their different properties, different EM waves are used for different purposes