Physics 120 - Chapter 21: Magnetic Fields Flashcards

Vocabulary practice flashcards covering the introduction to magnetic fields, Earth's magnetism, mathematical equations for force and field, and ferromagnetic materials.

Inductor

A device, represented by the letter "L" in RL circuits, consisting of copper looped around another material that produces a magnetic field when a charge is sent through it.

Magnetic Field ($B$)

A vector quantity with direction and magnitude that acts to steer charged particles and is perpendicular ($90^\circ$) to the electric field in an electromagnetic wave.

Einstein

The physicist who noticed that light could be represented as both a wave (EM wave) or a particle (photons).

Earth's Magnetic Field

The by-product of the spinning iron and nickel core of the planet that deflects dangerous charged nuclear particles from the sun.

Angle of Declination

The angle of deviation (approximately $12^\circ$) formed from the direction of the Earth's magnetic field lines and true north (geographical north pole).

Angle of Dip (Inclination)

The angle to the surface formed by a freely suspended magnetic needle, which varies by location and is equal to zero at the equator.

Dip Circle

An instrument used in the laboratory (as well as for surveying, mining, and prospecting) to determine the value of the Angle of Dip.

Magnetic Pole Reversal

The phenomenon where the Earth's poles switch places approximately every $800,000$ years.

Magnetic Resonance Imaging (MRI)

A medical imaging tool designed to read the human body's magnetic field lines, which are generated by moving electric fields within cells and radioactive properties of the body.

Tesla ($T$)

The SI unit of the magnetic field, named after the man responsible for the development of the AC system and wireless device theories.

Right Hand Rule (RHR)

A method used to find the direction of a magnetic field ($B$), current ($I$), or force ($F$) by positioning the thumb, fingers, and palm of the right hand.

Magnetic Field Equation (Magnitude)

$B = \frac{F}{q v \sin(\theta)}$, where "q" is the charge, "F" is the magnetic force, and "v" is the velocity.

Work ($W$) in a Magnetic Field

The work done by a magnetic field on a moving charge is equal to $0$ because the magnetic force acts at an angle of $90^\circ$ (perpendicular) to the particle's motion.

Centripetal Force ($F_c$)

The force that causes a charge "q" to move in a circular or semi-circular fashion when entering a magnetic field, defined as $F_c = \frac{m v^2}{r}$.

Magnetic Force on a Wire

Calculated by the equation $F = I B L \sin(\theta)$, used when a wire of a given length (L) carries a current (I) through a magnetic field.

Ferromagnetic

Materials where subatomic electron spins align to attract, including substances like Iron, Nickel, Cobalt, Chromium dioxide, and AlNiCo.