A magnet turns a compass needle, a charged rod pushes a charged thread aside, and Earth pulls a skydiver. What do the three forces share?
Rurik's radio plays music sent from a station's antenna across town. Something crossed the town, from the antenna to his radio. What is that something?
Light behaves as a wave, and a radio signal does too. This lesson says what that wave is made of.
You have met fields in earlier topics: the electric field around a charged object, and the magnetic field around a magnet.
In magnetism you also saw that an electric current makes a magnetic field around itself.
In the station's antenna, charges oscillate, so there is an oscillating current.
Around the antenna, the electric field oscillates, and the magnetic field oscillates with it.
Those two oscillating fields travel outward together as one wave, and that wave is Rurik's radio signal.
The two fields oscillate perpendicular to each other: each at right angles to the other.
Both fields also oscillate perpendicular to the direction the wave travels.
The two fields also oscillate in step: both rise together, both fall together, and both pass through zero together as the wave moves outward.
In the figure, each curve shows the strength of one field along the wave's path; where a curve meets the center line, that field is zero at that point.
A Wi-Fi signal crosses a bedroom. Name the two things that oscillate as it travels.
A Wi-Fi signal is an electromagnetic wave.
An electromagnetic wave is an oscillating electric field and an oscillating magnetic field, traveling together.
An electric field and a magnetic field oscillate, each perpendicular to the other and to the direction the signal travels.
A radio wave travels straight upward from an antenna. Its electric field oscillates north and south. Along which line does its magnetic field oscillate?
The magnetic field oscillates perpendicular to the electric field.
It also oscillates perpendicular to the travel direction, which is straight up.
The line perpendicular to both north-south and up-down runs east-west.
The magnetic field oscillates east and west.
A signal from a television station crosses the city to a rooftop antenna. What oscillates as the signal travels?
In an electromagnetic wave, how are the two oscillating fields arranged relative to each other?
Quenby says: 'In a radio wave, the electric field and the magnetic field oscillate in step as the wave travels outward.' Is Quenby correct?
Which statement describes an electromagnetic wave?
In a snapshot of an electromagnetic wave, the wave travels to the right and the electric field oscillates up and down. Along which line does the magnetic field oscillate?
Light from a lamp crosses a dark room to the far wall. What oscillates as the light crosses the room?