The difference in potential energy between two points is
equal to the negative of Work done by a force
ΔU = -Wab
Above equation is possible only for conservative forces which
means that potential energy can only be defined for conservative forcesForces
are conservative if and only if the work done by these forces when a body moves
from a to b is independent of the path taken between these two locationsFor
example work done by a force in the gravitational field is independent of the
path followed by the particle We can make a similar argument for the
electrostatic force with the same result Which means that the
electrostatic force is also conservative and can be demonstrated by potential
energy The only difference between the two is that gravitational force is
only attractive and electrostatic force can be attractive and repulsive both.
Consider system of two positive charges +q and q0
The charge q0 moves under the
influence of E field created by +q
The charge q0 moves a small
displacement dr as it moves from position A to position B
Magnitude of E field created by +q decreases
as the charge q0 moves farther away from charge +q
The charge q0 experiences a
force (F = q0 E ) that varies with
displacement
We need to calculate work done by a variable force
No comments:
Post a Comment