Glossary
Cathode Ray Tube (CRT)
A vacuum tube that contains an electron gun and a fluorescent screen, used to display images. Magnetic and electric fields are used to steer the electron beam to create the image.
Example:
Old television sets and computer monitors used a Cathode Ray Tube (CRT) to display images by deflecting electron beams.
Magnetic Field
A region around a magnetic material or a moving electric charge within which the force of magnetism acts. It is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials.
Example:
The Earth is surrounded by a magnetic field that protects us from solar radiation, guiding charged particles to create auroras.
Magnetic Field Lines
Imaginary lines used to visualize the direction and strength of a magnetic field. They originate from the north pole and terminate at the south pole, with their density indicating field strength.
Example:
Drawing magnetic field lines around a bar magnet helps visualize how a compass needle would align at different points.
Magnetic Field Strength (B)
A measure of the intensity of a magnetic field at a given point, representing the force exerted on a moving charge or current. It is a vector quantity, denoted by the symbol B.
Example:
A strong electromagnet can generate a high magnetic field strength (B), capable of lifting heavy metal objects.
Magnetic Force
The force exerted on a moving electric charge or a current-carrying wire when it is placed in a magnetic field. Its direction is perpendicular to both the velocity of the charge and the magnetic field.
Example:
The magnetic force on electrons moving through a wire in a motor causes the motor's shaft to rotate.
Mass Spectrometer
An analytical instrument that measures the mass-to-charge ratio of ions. It typically uses electric and magnetic fields to separate ions based on their trajectories.
Example:
Scientists use a mass spectrometer to identify unknown compounds by analyzing the mass of their constituent ions.
North Pole
One of two poles of a magnet, from which magnetic field lines are conventionally said to emerge. It is the pole that points towards the Earth's geographic North Pole.
Example:
When you hold two magnets, the north pole of one will repel the north pole of the other.
Right-Hand Rule (RHR)
A mnemonic used to determine the direction of the magnetic force on a positive moving charge, or the direction of the magnetic field produced by a current. For force, the thumb points to velocity, fingers to magnetic field, and the palm indicates the force.
Example:
Using the Right-Hand Rule (RHR), you can quickly determine that an electron moving east in a downward magnetic field experiences an upward force.
South Pole
One of two poles of a magnet, where magnetic field lines are conventionally said to terminate. It is the pole that points towards the Earth's geographic South Pole.
Example:
The south pole of a compass needle is attracted to the Earth's geographic North Pole.
Tesla (T)
The SI unit of magnetic field strength. One Tesla is defined as one Newton per ampere-meter (N/(A·m)) or one Newton-second per Coulomb-meter (Ns/(C·m)).
Example:
A typical refrigerator magnet has a field strength of about 0.01 Tesla (T), while an MRI machine can use fields of several Teslas.
Uniform Circular Motion (UCM)
The motion of an object moving at a constant speed along a circular path. In magnetism, it describes the path of a charged particle moving perpendicular to a uniform magnetic field.
Example:
A proton entering a uniform magnetic field perpendicular to its velocity will undergo uniform circular motion (UCM), spiraling in a perfect circle.
Velocity Selector
A device that uses perpendicular electric and magnetic fields to allow only charged particles with a specific velocity to pass through undeflected. The electric and magnetic forces balance each other for the desired velocity.
Example:
In a velocity selector, only particles moving at a specific speed will pass straight through, while others are deflected.