Medical physics

1. MEDICAL PHYSICS
Chapter No. 1
ELECTRICITY AND MAGNETISM
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2. Introduction
• The course covers the knowledge and application of
Medical Physics in the field of Physical Therapy.
• Medical Physics covers application of basic concepts,
laws, theories of Physics in health care and
Physiotherapy. Construction of the instruments used
in Electrotherapy.
• Understand the Basic concepts of Physics of
currents, production and physiological and chemical
effects.
• In medical physics we study the basic principal of
physics applied on modalities used in
physiotherapy.
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3. Table of content
• Structure of Atom
• States of matter
• Formation of compound
• Types of elements
• Transmission of heat
• Formation of compound
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4. 4

5. Atom
• John Dalton; matter is composed of atom.
• J.J Thompson; structure of atom.
• Rutherford; discovery of Nucleus.
• Neil Bohr; electronic arrangement
• Quantum Physics; atom consist of many sub atomic
particles.
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6. • Atom, tiny basic building block of matter. All the
material on Earth is composed of various
combinations of atoms. An atom consists of a cloud
of electrons surrounding a small, dense nucleus of
protons and neutrons. Atoms are the smallest
particles of a chemical element that still exhibit all
the chemical properties unique to that element.
• Diameter of atom is 10-10 m.
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Atom

7. 7

8. Structure of atom
Atom
Nucleus
Proton
Neutron
Shells Electron
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9. 9

10. Nucleus
• An atom consists of a cloud of electrons surrounding
a small, dense nucleus of protons and neutrons. The
nucleus contains nearly all of the mass of the atom,
but it occupies only a tiny fraction of the space inside
the atom. The diameter of a typical nucleus is only
about 1 × 10-15 m to 1 × 10-14 m.
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11. • Central part of an atom is nucleus.
• It has two particles proton and neutron (nucleon).
These are held together by nuclear forces.
• It has positive charge.
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Nucleus

12. RUTHERFORD’S MODEL
• Most of the positively charged “bullets” passed
right through the gold atoms in the sheet of gold
foil without changing course at all.
• Some of the positively charged “bullets,” however,
did bounce away from the gold sheet as if they had
hit something solid . He knew that positive charges
repel positive charges.
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13. Proton
• Proton (p+) was discovered by E.Goldstein. Proton
has 1 unit mass. Protons have a positive electrical
charge of 1.602 x 10-19 coulomb.
• This charge is equal but opposite to the negative
charge of the electron.
• A proton’s mass is about 1,840 times the mass of
an electron. Protons carry a positive charge of +1,
exactly the opposite electric charge as electrons.
• The number of protons in the nucleus determines
the total quantity of positive charge in the
atom.(atomic number).
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14. Neutron
• Neutron (n) was discovered by Sir James Chadwick.
• The neutron is slightly heavier than a proton and
1,838 times as heavy as the electron.
• Neutron, electrically neutral elementary particle
that is part of the nucleus of the atom.
• The neutron is about 10-13 cm in diameter and
weighs 1.6749 x 10-27 kg
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15. 15

16. Atomic mass / Atomic number
•The sum of protons and neutrons is called
atomic mass.
•Example Carbon12.
•The number of proton in an atom is called
atomic number. Example carbon 6.
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17. Isotopes
• In certain elements number of neutrons are
different in their nuclei. These are called isotopes.
• Example carbon 12, 13, 14.
• Isotope, one of two or more species of atom having
the same atomic number, hence constituting the
same element, but differing in mass number. The
nucleus, and mass number is the sum total of the
protons plus the neutrons in the nucleus, isotopes of
the same element differ from one another only in
the number of neutrons in their nuclei.
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18. ISOBARS
• The total number of nucleons is the same in the
atoms of this pair of elements.
• Atoms of different elements with different atomic
numbers, which have the same mass number, are
known as isobars.
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19. 19

20. Shells
• The electrons are arranged in definite energy
shell or orbits around the nucleus called principal
quantum shell.
• These are seven. K,L,M,N……
• Octets rule. 2n2.
• Each shell is divided into 4 sub shells, s,p,d,f.
• The electrons fill lowest shell first.
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21. 21

22. 22

23. Electrons
• Electrons (e-) were discovered by sir. J.J. Thomson.
• Electrons are tiny, negatively charged particles around
the nucleus of an atom.
• Each electron carries a single fundamental unit of
negative electric charge–1.602 x 10-19 coulomb and
has a mass of 9.109 x 10-31 kg.
• The electron is one of the lightest particles with a
known mass.
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24. • These are responsible for physical and chemical
activities of an atom.
• A strong force of attraction is present between
electron and nucleus.
• It obeys the inverse square law.
• F  1/d2
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Electrons

25. Bound electrons Valance electrons
• Electrons which are close
to the nucleus are tightly
bound. These are called
bound electrons.
• As the number of orbit
increases, the force of
attraction between
electrons and nucleus is
weak. As a result these
are free electrons.
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26. Ions
Positive ion cation Negative ion anion
• If an atom loses on
electron it becomes
positive ion.
• Example sodium ion
• If an atom gains on
electron it becomes
negative ion.
• Example chlorine ion
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27. 27

28. Matter
• Every thing that have weight and occupy space is
called matter.
• Cohesive forces are attractive forces between the
molecules of matter.
• Kinetic forces are movement of the
molecules.(vibrations)
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29. States of matter
States
Solids
Liquids
Gases
Plasma
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30. Solids
• Matter which have fix shape and fix volume.
• Cohesive forces are strongest.
• Kinetic forces are weak. Just about there mean position
• Strong m.p and b.p.
• Example wood. Iron. Glass.etc
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31. Liquids
• Matter having fix volume but not fix shape.
• They take the shape of container.
• Cohesive forces weak
• Kinetic forces are strong.
• Moderate m.p and b.p.
• Example water mercury.
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32. Gases
• Matter which do not have fix shape and fix volume.
• Cohesive forces weakest.
• Kinetic forces are strongest.(randomly)
• Example different gases oxygen nitrogen etc
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33. Plasma
• It is considered as forth state of matter.
• It consist of atoms, Ions, free electron, etc.
• It is in the form of semi solid.
• Universe is made up of plasma.
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34. 34

35. Types of elements
1. Conductors
2. Insulators
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36. Conductors
• Elements which allow passage of heat and
electricity are called conductors.
• These elements have free electrons in their outer
most shell. These electrons allow flow of heat.
• All metals are good conductor. Cupper, gold,
iron, etc
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37. Insulators
• elements which do not allow passage of heat and
electricity are called insulators.
• These elements do not have free electrons in their
outer most shell. Outer shells are completely filled.
• All non metals are insulators. Wood, carbon, glass, etc.
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38. Conductivity of Selected Materials
Conductors Fair Conductors Insulators
Copper
Water with dissolved
minerals
Rubber
Aluminum Moist Air Wood
Iron Human Body Plastic
Mercury Carbon Pure Water
Other metals Soil
Metal oxides such as
rust
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40. Heat
•It is a form of energy that is transferred from
one body to the other body as a result of
temperature difference.
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41. Transmission of heat
Methods
Conduction
Convection
Radiation
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42. Transmission of heat
• Heat has ability to transfer from area of higher
temperature to area of lower temperature.
• It is called temperature.
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43. Conduction
• Transmission of heat in solids is called conduction
• f one end of a metal rod is heated, it causes
increase in temperature at that end. Kinetic
forces of molecules increase. It conduct the heat
to the other end.
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44. Convection
• Transmission of heat in liquids
and gases is called convection.
• When fluid in a pot is heated,
kinetic energy increases,
molecules moves away from
each other, area become less
dense, the more fluid come to
take its place. The whole
process continues until the
temperature of liquid become
equal.
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45. Radiations
• Transmission of heat between air and vacuum is called
radiation.
• Transmission of heat from sun to earth isby radiation.
• Heat in vacuum is transmitted by
electromagnetic radiations.
• As a substance is heated, it cause electron to move the
higher energy shell. When the electron moves back to
lower energy shell. Energy is released in the form of heat.
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48. Compounds
Ionic compound Covalent compound
• These compounds are
formed by the complete
transfer of electrons.
• Example NaCl
• These compounds are
formed by the mutual
sharing of electrons.
• Example CH4
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49. THANKS
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