CHAPTER 15. EM RADIATION 15.3
The particle nature of light can be demonstrated by the interaction of photons with
matter. One way in which light interacts withmatter is via the photoelectric effect,
which will be studied indetail in Chapter 16.
Exercise 15 - 1
- Give examples of the behaviour of EM radiation which can best be explained
using a wave model. - Give examples of the behaviour of EM radiation which can best be explained
using a particle model.
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(1.) 01m2 (2.) 01m3
15.3 The wave nature of electromagnetic radiation
ESCGS
Accelerating charges emit electromagnetic waves. We have seen that a changing elec-
tric field generates a magnetic field and a changing magnetic field generates an electric
field. This is the principle behind the propagation of electromagnetic waves, because
electromagnetic waves,unlike sound waves, donot need a medium to travel through.
EM waves propagate when an electric field oscillating in one plane produces a mag-
netic field oscillating ina plane at right anglesto it, which produces an oscillating
electric field, and so on. The propagation of electromagnetic waves canbe described
as mutual induction.
These mutually regenerating fields travel through empty space at a constant speed of
3 × 108 m· s−^1 , represented by c.
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