c
Wednesday, January 30, 2008
d
Force
In physics, force is what causes a mass to accelerate. It may be experienced as a lift, a push, or a pull. The acceleration of the body is proportional to the vector sum of all forces acting on it (known as the net force or resultant force). In an extended body, force may also cause rotation, deformation, or an increase in pressure for the body.F = I * L * B
Where:
F=Force
I=Current
L=Length
B=Magnetic Field
In physics, the magnetic field is a field that permeates space and which exerts a magnetic force on moving electric charges and magnetic dipoles. Magnetic fields surround electric currents, magnetic dipoles, and changing electric fields.
Fleming's left hand rule
the use of right hand
Direction of force
The direction of force is determined by the above equations, in particular using the right-hand rule to evaluate the cross product. Equivalently, one can use Fleming's left hand rule for motion, current and polarity to determine the direction of any one of those from the other two, as seen in the example. It can also be remembered in the following way. The digits from the thumb to second finger indicate 'Force', 'B-field', and 'I(Current)' respectively, or F-B-I in short. Another similar trick is the right hand grip rule.
In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field (can also be equated to "Electric Flux Density"). This electric field exerts a force on other electrically charged objects. The concept of electric field was introduced by Michael Faraday.
Similarities between electrostatic and gravitational forces:
- Both act in a vacuum.
- Both are central and conservative.
- Both obey an inverse-square law (both are inversely proprotional to square of r).
- Both propagate with finite speed c.
- Differences between electrostatic and gravitational forces:
- Electrostatic forces are much greater than gravitational forces (by about 1036 times).
-Gravitational forces are attractive for like charges, whereas electrostatic forces are repulsive for like charges.
-There are no negative gravitational charges (no negative mass) while there are both positive and negative electric charges. This difference combined with previous implies that gravitational forces are always attractive, while electrostatic forces may be either attractive or repulsive.
- Electric charges are invariant under Lorentz transformations while gravitational charges (relativistic mass) are not.
It's Better To LEARN nothing than to KNOW nothing
lured into a deep sleep at Wednesday, January 30, 2008 1 person(s) commented while I sleep
lured into a deep sleep at Wednesday, January 30, 2008 1 person(s) commented while I sleep