Magnetic domain
A region composed of a group of atoms whose magnetic fields are aligned in the same direction.
Magnetic Field
A region whose magnetic force can be detected.
Solenoid
A long, helically sound cool of insulated wire.
Electromagnetic induction
The process of creating a current in a circuit loop by changing the magnetic flux in the loop.
Generator
A machine that converts mechanical energy into electrical energy.
Alternating current
An electric current that changes directions at regular intervals.
Back emf
The emf induced in a motor's coil that tends to reduce the current in the coil of the motor.
Mutual inductance
Th ability of one circuit to induce an end in a nearby circuit in the presence of a changing current
Rms current
The value of alternating current that gives the same heating effect that the corresponding value of direct curent does
Transformer
A device that increases or decreases the emf of alternating current.
Electromagnetic Radiation
The transfer of energy associated with an electric and magnetic field; it varies periodically and travels at the speed of light.
Photon
A unit or quantum of light; a particle of electromagnetic radiation that has zero mass and carries a quantum energy.
What is the direction of any magnetic field defined as?
The direction the north pole of a magnet would point if placed in the field. The magnetic field of a magnet points from the north pole of the magnet to the south pole.
What is the magnetic field created by a solenoid or coil similar to?
-The magnetic field of a permanent magnet.
Describe the magnetic field existing around any current-carrying wire.
-Every current-carrying wire has a magnetic field
-It follows a circular path around the wire
When two current-carrying wires are parallel, they
Exert on one another forces that are equal in magnitude, but opposite in direction.
If two current-carrying wires have currents in the same direction, do they attract or repel each other?
They attract one another.
Lenz's Law
States that the magnetic field of an induced current opposes the change that caused it.
What does Faraday's law of induction calculate?
The magnitude of the induced emf.
What does a generator use to convert mechanical energy into electrical energy?
Induction.
Motors
Use an arrangement similar to that of generators to convert electrical energy into mechanical energy.
What are important measures of an ac circuit?
-The rms current and rms emf
What are electromagnetic waves?
Transverse waves that are travelling at the speed of light and are associated with oscillating electric and magnetic fields.
What do electromagnetic waves do with energy?
They transfer it.
Where is the energy of electromagnetic waves stored?
In the waves' electric and magnetic fields.
What do radio waves, microwaves, X rays, and gamma rays all have in common?
They are all electromagnetic waves.
What is not a way to induce an emf in a loop of wire?
Moving the loop parallel to a magnetic field?
Describe a modification to a solenoid which would most likely decrease the strength of its magnetic field.
-Decreasing the current
-reducing the number of coils
What does the operation of an electric motor depend on?
The magnetic force acting on a current-carrying wire.
What is an electric current that changes directions at regular intervals is called?
Alternating current
A current in a long, straight wire produces a magnetic field. These magnetic field lines...
Form concentric circles around the wire
Electromagnetic waves are ________ electric and magnetic fields.
oscillating
In soft magnetic materials such as iron, what happens when an external magnetic field is removed?
It returns to its unmagnetised state.
Describe ways that electricity may be generated.
-Move the circuit loop into and out of a magnetic field
-Change the magnetic field strength around the circuit loop
-Change the orientation of the circuit lop with respect to the magnetic field.
-Rotating a loop of wire between the poles of a magnet.
In a magnetised substance, the domains
Align themselves in one general direction
Where is the magnitude of the magnetic field around a permanent magnet greatest?
Closest to the poles.
In a two-coil system, the induced potential difference in the secondary coil depends on what????
The number of turns, doofus!
Who is the cutest boy in the eleventh grade?
- Scott Garber.
Connor Wales is also acceptable.
The induced current of electricity generated by rotating a loop of wire between the poles of a magnet is greatest when
When the coil is parallel to the magnetic field.
Describe Earth's magnetic declination
The angle between true North, and North indicated by the compass.
Does dropping a strong magnet down a long copper tube induce a current in the tube? If so, what effect will the induced current have on the motion of the magnet?
Yes. It should oppose the motion of the magnet, slowing it.
Where does domain alignment persist after the external magnetic field is removed?
In a permanent magnet.
The direction of the force on a current-carrying wire in an external magnetic field is
Perpendicular to both the current and the magnetic field.
According to the right-hand rule, if a current-carrying wire is grasped in the right hand with the thumb in the direction of the current, the four fingers will curl in the direction of...
The magnetic field
An electron moving north encounters a uniform magnetic field. If the magnetic field points East, what is the direction of the magnetic force on the electron?
Into the page in the positive direction.
What is an emf?
Emf is the average voltage de loped by any source of electrical energy such as a battery or Dynamo.