Partial Notes on Radiologic Physics 2
ELECTRICITY AND MAGNETISM
- has mass and energy equivalence and may also have electric charges
- Electrically neutral which means, in the entire universe the total number of positive charge is equal to the total number of negative charge.
- derived from the word electricity
- Can be created by contact, friction and induction
- Due to the movement of negative electric charges.
• The primary function of x-ray tube is to convert electric energy to EMR or x-rays.
Two Studies of Electric Charges
- Electrostatics– the study of electric charges in stationary form.
- Electrodynamics– the study of electric charges in motion.
Four Fundamental Properties of Matter
- Energy equivalence
- Electric charge
2 Units of Electric Charges
- electrons- the smallest unit of electric charge.
- proton- positively charge particle.
● Earth- huge reservoir for stray electric charge.
Four Electrostatics Law
- Unlike charges attract, like charges repel.
● Electrostatic Force- the force of attraction between unlike charges or repulsion between like charges which is due to the electric field.
2. Coulombs’ Law– states that electrostatic force is directly proportional to the product of the electrostatic charges and inversely proportional to the distance between them.
3. Electric Charge Distribution– states that electric charge distribution is uniform through out or on the surface.
4. Electric Charge Concentration– states that electric charges are concentrated along the sharpest curvature of the surface.
- Is also known as electricity
Electric Current – the flow of electron and occurs in many types of objects.
Conductors and Insulators
- Conductor– is a substance through which e- flow easily
- Insulator– any material that does not allow the flow of e- or inhibits the flow of electrons
- possesses two properties of a conductor and insulator.
- the property of the material to exhibits no resistance below a critical temperature.
Four Electric States of Matter
- Superconductors– possesses no resistance to electron flow (niobium and titanium)
- Conductor– it obeys Ohms’ Law and requires a voltage (copper and aluminum)
- Semi-conductor– can be conductive and can be resistive (silicon and germanium)
- Insulators– do not permit e- flow (glass and rubber)
● 1 ampere= 1 flow of e-/sec