ATOMS - ANSWER-FUNDAMENTAL SUBMICROSCOPIC UNIT OF ALL MASS. SIZE OF THE ATOM AND ITS WEIGHT HAVE INTERESTED SCIENTISTS FOR A LONG PERIOD. SUBSEQUENTLY, EXPERIMENTS WERE DEVISED TO DETERMINE THE SIZE AND WEIGHT OF THE VARIOUS ATOMS. THE LIGHTEST OF ALL ATOMS IS HYDROGEN.
PROTON - ANSWER-A SUBATOM...
ATOMS - ANSWER-FUNDAMENTAL SUBMICROSCOPIC UNIT OF ALL MASS. SIZE
OF THE ATOM AND ITS WEIGHT HAVE INTERESTED SCIENTISTS FOR A LONG
PERIOD. SUBSEQUENTLY, EXPERIMENTS WERE DEVISED TO DETERMINE THE
SIZE AND WEIGHT OF THE VARIOUS ATOMS. THE LIGHTEST OF ALL ATOMS IS
HYDROGEN.
PROTON - ANSWER-A SUBATOMIC PARTICLE HAVING A POSITVIE CHARGE
IDENTICAL IN MAGNITUDE TO THE NEGATIVE CHARGE OF AN ELECTRON AND,
TOGETHER WITH THE NEUTRON, A COMPONENT OF ALL ATOMIC NUCLEI. THE
PROTON FORMS, BY ITSLEF, THE NUCLEUS OF THE HYDROGEN ATOM. THE
MASS OF A PROTON IS APPROXIMATELY 1836 TIMES THAT OF AN ELECTRON
AND THE MASS OF AN ATOM IS CONTAINED ALMOST ENTIRELY IN THE
NUCLEUS. THE PROTON HAS AN INTRINSIC ANGULAR MOMENTUM OR SPIN
AND THUS A MAGNETIC MOMENT (VERY SMALL MAGNETIC FIELD). THE
NUMBER OF PROTONS IN THE NUCLEUS OF AN ATOM DETERMINES WHAT
ELEMENT IT IS; THE ATOMIC NUMBER OF AN ELEMENT DENOTES THE NUMBER
OF PROTONS IN THE NUCLEUS.
ELECTRON - ANSWER-A SUBATOMIC MPARTICLE THAT, ALONG WITH PROTONS
AND NEUTRONS, MAKE UP THE ATOMS THE FLOW OF AN ELECTRIC CURRENT
IN A CONDUCTOR IS CAUSED BY THE DRIFTING OF FREE ELECTRONS IN THE
CONDUCTOR. HEAT CONDUCTION IS ALSO PRIMARILY A PHENOMENON OF
ELECTRON ACTIVITY. THE CHARGE OF THE ELECTRON IS THE BASIC UNIT OF
ELECTRICITY. ELECTRONS HAVE HALF-INTEGRAL SPIN; SPIN IS A PROPERTY
OF SUBATOMIC PARTICLES THAT INDICATES THE PARTICLE'S ANGULAR
MOMENTUM.
NEUTRON - ANSWER-A SUBATOMIC PARTICLE THAT IS NEUTRAL THEREFORE
HAS NO CHARGE. IT IS LOCATED IN THE NUCLEUS AND SERVES AS A
STABILIZER. THE MASS OF A NEUTRON IS SLIGHTLY GREATER THAN THE
PROTON MASS AND HAS AN ENORMOUS EFFECT ON THE QUANTUM SPIN
VALUE OF AN ELEMENT. THE NET CHARGE ON A NEUTRON IS 0
MAGNETISM - ANSWER-IS DESCRIED AS THE ABILITY OF A SUBSTANCE TO
ATTRACT IRON, COBALT AND NICKEL. IT IS THE POWER OR FORCE CREATED
BY A SUBSTANCE HAVING THE PROPERTY OF CREATING OR INDUCING
MAGNETIC DIPOLES. THE MAGNETIC FIELD OF ANY MAGNET HAS A
DIRECTION, SIGNIFIED NORTH AND SOUTH. THIS PROPERTY OF A MAGNET
MAKES IT A DIPOLE. DIPOLE - A MAGNETIC FIELD CHARACTERIZED BY ITS OWN
MAGNETIC NORTH AND SOUTH POLES SEPARATED BY A FINITE DISTANCE.
,MAGNETIC SUSCEPTIBILITY - ANSWER-DEFINED AS THE TENDENCY OF A
SUBSTANCE TO ATTRACT OR REPEL MAGNETIC LINES OF FORCE DEPENDENT
ON THE MAGNETIC PROPERTIES OF ITS ELECTRONS.
DIAMAGNETIC - ANSWER-THE PROPERTY OF MOST SUBSTANCES WITH
PAIRED ORBITAL ELECTRONS THAT HAVE OPPOSITE SPINNING AND THEIR
MAGNETIC MOENTS CANCEL EACH OTHER OUT. SUBSTANCES WITH
DIAMAGNETIC SUSCEPTIBILITY WEAKLY ATTRACT OR REPEL MAGNETIC LINES
OF FORCE. MAGNETIC SUSCEPTIBILITY OF MOST HUMAN BODY TISSUES ARE
DESCRIBED AS DIAMAGNETIC.
PARAMAGNETIC - ANSWER-THE PROPERTY OF SUBSTANCES WITH POSITIVE
MAGNETIC SUSCEPTIBILITY THAT ATTRACT AND REPEL MAGNETIC LINES OF
FORCE. THESE SUBSTANCES (GADOLINIUM, METHEMOGLOBIN, FREE
RADICALS) CONTAIN ONE OR MORE UNPAIRED ORBITAL ELECTRONS AND
PRODUCE MARKED REDUCTIONS IN THE T1 AND T2 RELAXATION TIMES.
UNPAIRED ORBITAL ELECTRONS SPIN IN THE SAME DIRECTION AND HAVE THE
TENDENCY TO LINE UP WITH THE MAGNETIC FIELD. THEREFORE PRODUCING
ADDITIONAL MAGNETIC FIELDS.
SUPER-PARAMAGNETIC - ANSWER-THE PROPERTY OF SUBSTANCES WITH
LARGE POSITIVE MAGNETIC SUSCEPTIBILITY WHICH STRONGLY ATTRACT OR
REPEL MAGNETIC LINE SOF FORCE. THESE SUBSTANCES (HEMOSIDERIN AND
SUPERPARAMAGNETIC IRON OXIDE -SPIO) HAVE A SINGLE MAGNETIC DOMAIN
AND ARE MAGNETIZED IN A MAGNETIC FIELD. THEIR MAGNETIC
SUSCEPTIBILITIES ARE MUCH LARGER THAN THOSE OF PARAMAGNETIC
SUBSTANCES AND SIMILAR TO THOSE OF FERROMAGNETIC MATERIALS.
UNLIKE FERROMAGNETIC SUBSTANCES, SUPERPARAMAGNETIC MATERIALS
DO NOT EXHIBIT RESIDUAL MAGNETISM WHEN THE EXTERNAL FIELD IS
REMOVED.
FERROMAGNETIC - ANSWER-THE PROPERTY OF SUBSTANCES WITH LARGE
POSITIVE MAGNETIC SUSCEPTIBILITY THAT BECOME MAGNETIZED WITHIN A
MAGNETIC FIELD AND REMAIN MAGNETIZED AGTER BEING REMOVED FROM
THE MAGNETIC FIELD. FERROMAGNETIC SUBSTANCES INCLUDE A NUMBER OF
IRON AN COBALT-CONTAINING METALS.
MAGNETIC FIELD - ANSWER-A VECTOR QUANTITIY CONSISTING OF BOTH A
NORTH AND SOUTH POLE; IT EXERTS AN INDUCTION FORCE ON
FERROMAGNETIC AND PARAMAGNETIC SUBSTANCES. WHEN SYMBOLIZING
THE FLOW AND AREA OF A MAGNETIC FIELD, SPECIAL LINES ARE USED; THEY
ARE FIELD OR FLUX LINES
FIELD OR FLUX LINES - ANSWER-MEASURE THE FLOW AND AREA OF A
MAGNETIC FIELD. THE STRONGEST AREA OF THE MAGNETIC FIELD IS WHERE
, THE FIELD OR FLUX LINES CONVERGE AND IS CALLED THE ISOCENTER. AWAY
FROM THE ISOCENTER THE FIELD OR FLIX LINES REPRESENT THE FRINGE
FIELDS.
ISOCENTER - ANSWER-AREA OF THE MAGNETIC FIELD WHERE THE FIELD
STRENGTH IS THE GREATEST, IN MRI THE CENTER OF THE SCAN AREA
FRINGE FIELDS - ANSWER-WEAKER MAGNETIC FIELDS THAT ARE AWAY FROM
THE ISOCENTER, IN MRI OUTSIDE OF THE SCANNING AREA.
FLUX - ANSWER-FLOW OF ENERGY; MAGNETIC FIELD FLOWING FROM NORTH
TO SOUTH POLES REPRESENTED BY MAGNETIC LINES OF FORCE.
FORCE - ANSWER-THE ABILITY TO CREATE WORK OR CHANGE (MEASURED IN
HORSEPOWER). WHEN DESCRIBING THE STRENGTH OF AN MRI MAIN
MAGNETIC FIELD, THE SI UNIT MOST COMMONLY USED IS TESLA. A SYMBOL
TO DESCRIBE THE DIRECTION AND STRENGTH OF A MAGNETIC FIELD IS
CALLED VECTOR.
VECTOR - ANSWER-A MATHEMATICAL ENTITIY CHARACTERIZED BY STRENGTH
(MAGNITUDE) AND DIRECTION. VECTOR QUANTITIES CAN BE ADDED OR
SUBTRACTED FROM ON ANOTHER. VECTORS WITH THE SAME DIRECTION -
ADD UP; OPPOSITE DIRECTION - CANCEL EACH OTHER OUT. THE SYMBOL
USED TO DESCRIBE THE STATIC (MAIN) MAGNETIC FIELD AND ITS VECTOR IS
BO.
HOMOGENEITY - ANSWER-TERM USED TO DESCRIBE MAGNETIC UNIFORMITY
IN THE LARGE STATIC MAGNETIC FIELD IS HOMOGENEITY. THE SPECIFICATION
THAT IS ACCEPTABLE FOR FIELD HOMOGENEITY OF AN MRI MAGNET FOR
CLINICAL SCANNING IS 20-30 PP M
FARADAY'S LAW - ANSWER-IN A LOOP OF CONDUCTOR WHERE AN ELECTRIC
CURRENT IS INTRODUCED AND MAINTAINED, A MAGNETIC FIELD WILL BE
PRODUCED IN THE CENTER. THIS IS ALSO TRUE INVERSELY.
FLEMINGS RIGHT HAND RULE - ANSWER-IF THE ELECTRON FLOW IS IN THE
DIRECTION OF THE CURLED FINGERS, THE THUMB WILL POINT IN THE
DIRECTION OF ITS MAGNETIC NORTH POLE.
FLEMING'S RIGHT HAND, THUMB UP RULE - ANSWER-SHOWS NORTH AND
SOUTH POLSES OF MAGNET. IF TH ELECTRON FLOW IS THE COUNTER
CLOCKWISE DIRECTION, THE THUMB WILL POINT IN THE DIRECTION OF ITS
MAGNETIC NORTH POLE. IF THE ELECTRON FLOW IS IN THE CLOCKWISE
DIRECTION, THE THUMB WILL PONT IN THE DIRECTION OF ITS MAGNETIC
SOUTH POLE.
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