Chapter 8 Electric Fields Flashcards
Define electrostatic induction?
Definition = when a charged object attracts an uncharged object.
Explain how electrostatic induction works?
Charged object goes near neutral one, causes electrons to either be attracted or repelled, thus creating a force between the two objects.
Explain how you can make an object charged?
When an insulator (eg plastic) is rubbed against another insulator it may become electrically charged (friction causes electrons to move from one object to the other).
Difference between radial and uniform field?
Radial field spreads out in all directions
Uniform field has same strength at all points
What do radial, uniform and charge above Earth diagrams all look like?
Look in notes
Which direction do arrows in field diagrams point?
From positive to negative
2 factors of field lines?
Spacing (shows strength)
Arrows (shows direction)
Define electric field strength?
The force per unit positive charge at a point (N/C or V/m)
Equation for electric field strength? (2)
E=F/Q
E=V/d
d is separation between plates
Force acting on a charge in an electric field equation? (2)
F=QE
F=QV/d
Define Coulombs Law? (With proportionality bit)
Any two point charges exert an electrical force on each other that is proportional to the product of their charges and inversely proportional to the square of the distance between them.
F = k(Qq/r^2)
Electrical force equation for point charges?
F=Qq/(4πε0r^2)
What is ε0?
Permittivity of free space = 8.85x10^-12F/m
Explain an experiment to investigate Coulomb’s law?
Polystyrene balls coated in silver are positively charged, one is on scales and the other is attached above it. As the ball is lowered toward the ball on the scales, the reading increases since F is proportional to 1/separation squared.
Electric field strength for a charge in a radial field?
E=force/test charge
E= Q/(4πε0r^2)
