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Radiography requires you to deliver radiation (a form of _____) to a patient (who is ____).
Energy, Matter
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Significant Digits rules
1) Every nonzero digit is significant. So count all nonzero digits (Step 1).
1,142 has 4 significant digits
2) Zeros between nonzero digits are always significant. So count all zeros between nonzero digits (Step 2).
50.024 has 5 significant digits
3) Zeros before nonzero digits are never significant.
0.12 has 2 significant digits .0005 has 1 significant digit
4) Zeros behind nonzero digits are sometimes significant. So only count all zeros at the end of a decimal value (Step 3).
Zeros are significant if they are at the end of a decimal value: 6.250 has 4 significant digits (the measurement 6.250 is precise to the thousandths place)
Zeros are not significant if they are after nonzero digits but before the decimal point: 6250 has 3 significant digits (the measurement 6250 is precise to the tens place)
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_____ - anything that takes up space & has form or shape
Matter
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____ - the ability to do work
Energy
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____ - is the force that an object exerts under gravity.
Weight
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____ - is a force of attraction that exists between any two masses, any two bodies, or any two particles.
Gravity
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Objects that fall to earth do so at a constant rate, called the ________.
Acceleration of Gravity (g)
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Matter has _____, which is the quantity of matter contained in an object
Mass
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_________ - was a proponent of this idea, believing that regardless of the number of times you cut a form of matter in half, you would always have a smaller piece of that matter
Aristotle (384-322 BC)
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______ - put forth the idea that all matter was formed from different types of tiny particles he called “atomos” (Greek for indivisible or unable to be cut)
Democritus (460-370 BC)
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English schoolteacher who published a book in 1808
•Elements differentiated from each other based on mass; atoms of a particular element react the same way chemically
John Dalton
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Russian scientist who developed Periodic Table of the Elements in 1869
•Arranged the known elements in order of increasing atomic mass & on the basis of similar chemical properties
Dmitri Mendeleev
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English physicist developed a nuclear model of the atom in 1911
•Atom has a (+) charged dense center (nucleus) surrounded by a (-) charged cloud of electrons
Ernest Rutherford
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Danish physicist proposed a model for the atom in 1913 – still widely used in explaining the composition of atoms
•Atom is a miniature “solar system” where electrons revolve around nucleus in fixed orbits
Niels Bohr
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Austrian physicist who in 1926 abandoned the idea of precise electron orbits & replaced them with a description of the regions of space around the nucleus called “orbitals”
•The orbitals are probabilities for location of where electrons were most likely to exist within an atom at any given moment in time
•The greatest probabilities are associated with Bohr’s model
•This is the foundation of modern physics called quantum (wave) mechanics
Erwin Scrodinger
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When energy is transmitted through matter, it is called ______.
Radiation
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The 6 types of energy are?
- •Mechanical
- •Chemical
- •Thermal
- •Electrical
- •Nuclear
- •Electromagnetic
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____ ____ - energy stored in an object based on position.
Potential Energy
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___ ___ - energy of motion.
Kinetic Energy
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__ __ __ - (c) = 3.0 x 108 m/s or 186,000 miles/sec.
Speed of Light
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4.15 x 10-15 eV-sec.
Planks Constant
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E = hv or v = E/h
Planks Law
- •E = photon energy (eV)
- •h = Plank’s constant (4.15 x 10-15 eV-sec.)
- •v = photon frequency (Hz)
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