Magnetic Fields Flashcards
What is an electromagnetic force?
A type of physical interaction that occurs between electrically charged particles.
What is an electric field?
The region of force around a charged object.
How is a magnetic field made around a charged object?
Magnetic fields are created as long as the charged object is in motion.
Example: A wire carrying a current.
How is the magnetic field oriented around a current-carrying wire?
The magnetic field around a current-carrying wire is always perpendicular to that wire.
How does the strength of a magnetic field relate to the current in a current-carrying wire?
The strength is proportional to the current. (If the current doubles, the strength doubles)
How is the distance related to the strength of a current-carrying wire?
The strength is inversely related to the distance from the wire. (The farther you are from the magnetic field, the weaker the magnetic field strength)
How do magnetic field lines emerge from the poles of a magnet?
They emerge from the magnet’s North Pole and enter at its South Pole. These field lines form closed loops around the magnet.
What are field lines used for?
Field lines are used to show the strength and direction of the magnetic field.
Describe the right-hand rule for finding the direction of a magnetic field around a current-carrying wire.
Imagine holding a wire with your right hand. If your thumb is pointing in the direction of the “conventional current” (positive charge flowing from positive to negative), the fingers of your hand encircling the wire will point in the direction of the magnetic field.
What is a solenoid?
A solenoid is a wire connected to a circuit and coiled into many spiraled loops.
What is an electromagnet?
An electromagnet is a magnet whose magnetic field is produce by an electric current.
Describe the right-hand rule for finding the direction of the magnetic field around a solenoid.
If you curl your fingers around the solenoid in the direction of the conventional (positive) current, your thumb will point in the direction of the magnetic field (North pole).
What is electromagnet induction?
When a magnetic field induces a current in circuit by moving a wire through the magnetic field.
What important technologies were created because of the discovery of electromagnetic induction?
Electric motors and generators.
Describe Lenz’s Law.
According to Lenz’s Law, the direction of the current is such that the magnetic field resulting from the induced current opposes the motion that is caused by the current.
How can electromagnet induction explain the creation of Earth’s magnetic field?
It is caused by the solid iron core at the centre of the Earth spinning at a different rate than the surface of Earth. This spinning, as well as radioactive decay in the iron core, causes convection currents which heat the liquid metal outer core, resulting in a magnetic field.
How does Earth’s magnetic field protect us?
Earth’s magnetic field extends from the centre of the Earth out into space, protecting us from space radiation and solar wind (a stream of charged particles emanating from the Sun).
What is the effect of short term changes to Earth’s magnetic field?
It is said that the magnetic field is weakening in some spots, and strengthening in others. In the weakened spots, there is a greater chance for solar storms to reach earth which would affect power grids, influence GPS navigation, and disrupt radio communications.
What is the effect of long term changes to Earth’s magnetic field?
Scientists are predicting that the poles will eventually flip (North becomes south), which will affect birds, fish, and any other animal that uses Earth’s magnetic field for navigation. This is said to happen every 300,000 years.
What kinds of technologies have been created through the discovery of electromagnetism?
Radar, tv, radio, toasters, microwaves, satellites, remote controls.
