Medical Physics lecture 3

2. STATIC ELECTRICITY
By:Dr Ansa Tahir
MPH General
Pharm-D

3. LEARNING OBJECTIVES
Understand the
• Electrostatics Induction
• Electric Field
• Electrical Potential
• Difference of Potential

4. CHARGING BY CONDUCTION
• Charging an object by contact with a charged
object.
• It is also called as
Charging by contact.
• It involves the direct
contact of a charged
object to a neutral
object.

6. ELECTROSTATIC INDUCTION
Induction may be defined as the production
of electric or magnetic properties in one
object by another without contact between
them.(1,2)

8. ELECTRIC FIELD
An electric field is the physical field that
surrounds each electric charge and exerts
force on all other charges in the field, either
attracting or repelling them. (4)

9. Electric Lines of Force
The forces resulting from the charge act along
definite lines known as the electric lines of
force.(1,3)

11.  They show certain properties.
 The lines of force surrounding an isolated charged body are straight.
 Line of force repel one another (as do like charges)
 Line of forces pass through more easily through conductor than through
insulator`.
 Lines of force concentrate on that part of surface of a charged body
nearest to another object over which they can exert an influence.
 If two bodies with opposing charges are placed opposite one another
there is force of attraction between them.
 If two similarly charge object are placed near one another, they repel.
 If charged body is placed in contact with an other body (charge or un
charge), then electron flow between them until they are at the same
potential

12. ELECTRIC POTENTIAL
The properties shown by charged body result
from the stored up or potential, energy of its
electric charge and its electrical condition is
referred to as its Electric Potential.
The unit of potential is the volt

13. Factors Determining Potential
The magnitude of the potential depends on
• The quantity of electricity
• The capacity of the object

14. The capacity of object depends upon
• The Material
• The surface area

15. Formula of Electrical Potential
• E for potential measured in volts
• Q quantity of charge in coulombs
• C for capacity measured in farads
E= Q/C

16. Measurement of capacity=?

17. Difference of Potential
When two objects are in a different state of
electric charge a difference of potential is said
to exist between them.
EMF
The movement of electrons constitutes an
electric current and is produced by a force
known as electromotive force

19. Refrences
• 1.Pauline M .Scott for Claytons Electrotherapy and
Actinotherapy
• 2.https://youtu.be/mL6Zb2pO9CA
• 3. https://youtu.be/F1z5UaX96j8
• 4.https://en.wikipedia.org/wiki/Electric_field

20. THANK YOU