Electric Fields Flashcards
Principle of Conservation of Charge
states that charge cannot be created or destroyed. hence for any closed system, the algebraic sum of all electric charges must be constant
Electric Field
a region of space where a charge will experience an electric force
Electric Field strength + what to take note of ?
electric field strength at a point is the electric force per unit positive charge acting on a small test charge placed at the point
pls mod if they ask for magnitude
What are electric field lines ?
It is the direction of electric force experienced by a positive charge if placed at that point
the number of lines leaving positive charge and approaching negative charge is PROPORTIONAL to the magnitude of the charge
Direction of E Field strength
Direction of electric field strength E at point in an electric field is tangent to the electric field line at that point
Electric Potential V
there was some impt stuff in the class test I think abt drawing Rembrandts to check
Electric potential V at a point is the work done per unit positive charge by an external force in bringing a small test charge from infinity to that point, without any change in KE energy
A positive charge placed & released in an E field will accelerate in the direction of E & gain KE, while simultaneously, lose EPE.
A negative charge caused to move {i.e. projected} in the direction of E will decelerate, i.e. lose KE & gain EPE.
For a pair of parallel plates, the potential decreases at a constant rate with distance from one of the plates
For a charged metal sphere, potential V within the sphere is constant & electric field strength is zero (due to its mobile charge carriers)
Inside a charged conductor, the electric potential is constant and non-zero everywhere, but the electric
field is zero
E = -dv/dx and F=-dU/dr, what does the negative sign indicate
The negative sign indicates that the electric field strength vector acts in the direction of decreasing potential.
The force on the charge points in the direction of decrease in potential energy
Equipotential surface
a surface on which every point has the same potential and the electric potential is constant
