Topic 4.1 EM Waves Flashcards
How are EM waves produced?
They are produced from oscillating charges. The charge will produce an E field due to its charge and a B field as it is oscillating.
Explain the relationship between the magnetic and electric fields of an EM wave
They are at right angles to each other
A changing magnetic field will produce an electric field.
A changing electric field will produce a magnetic field.
Changing field = oscillating field
Therefore, EM waves are self propagating
What is the plane of polarisation?
The plane of the oscillating E field
How should the receiving antenna be orientated to best receive the signal?
In the same direction as the transmitting antenna
What is an EM wave?
A electromagnetic wave consists of a magnetic field and electric field oscillating at right angles to each other
Explain the transmission and reception of radio or television waves in terms of the frequency of the oscillation of electrons in the transmitting and receiving antenna.
A potential difference in the antenna causes the electrons to move up and down the antenna. The pd dictates the acceleration of the electron and thus the frequency of the produced EM waves.
The waves will cause the electrons in the receiving antenna to oscillate at the same rate and thus produce the same image or sound.
Relate the orientation of he receiving antenna to the plane of polarisation
The plane of polarisation will be parallel to the orientation of the antenna.
TF, the receiving antenna should be parallel to the E field and perpendicular to the B field to best receive the signals and recreate the electrons oscillation.
