Em Flashcards
Electromagnetic waves are not a mechanical wave which requires a medium
It is a wave that travels through a vacuum( a space entirely devoid of matter)
Types of electromagnetic waves : good xylophones use very interesting musical rhythm orrrr raging Martians invaded venus using x rays guns
Gamma rays; x-rays; ultraviolet rays; visible light ; infrared; microwaves ; radio waves
Why aren’t em waves mechanical waves?
They transfer energy and don’t require a medium. Electromagnetic waves don’t disturb particles and it consists of varying electric and magnetic fields like radio waves and microwaves.
A changing magnetic field is able to set up an induced current or electric current
For equatuons ofjames clerk maxwell
There is an electric field around a point charge
A changing magnetic field can induce a changing electric field. A magnetic field is set up whenever charge moves and due to electric field.
Electric charge is always conserved.
Definition of em waves
Form when electric charges oscillate rapidly. An electron vibrating up and down in the vertical plane produces an electromagnetic wave which moves away from it at 90.
The oscillating charge
Changes it position and velocity so the electric and magnetic field it produces are continually changing. These changing fields induce other magnetic and electric fields in their vicinity and the electromagnetic disturbance travels outwards.
The electric field is parallel to
the motion of the electron. It increases and decreases in strength reversing direction periodically. The magnetic field is perpendicular to the electric field and it increases, decrease and reverses in the same way. The flactuations in the strengths of the fields are in phase and have a transverse wave character.
Why are em waves transverse waves?
The changing magnetic and electric fields are at right angles to each other and to the direction of wave travel m
Where can em waves travel
Through a material medium and through a vacuum because electric and magnetic fields can exist in both material media and in a vacuum.
How is a wave a disturbance
It can carry energy from one place to another through a medium
When the wavelength decreases
The frequency the wave increases. The period is the time taken to complete one cycle. The frequency is the number of cycles that it can make in one second.
F
1 /T (Hz)
E(electromagnetic)
Speed of light and strength of magnetic field
E= C. B
