7.3 Electric fields Flashcards
What do electrical conductors contain a lot of?
Free electrons.
What do electrically insulating materials not contain?
Free electrons.
What are free electrons?
Electrons which move about inside the metal and are not attached to any one atom.
What happens when a charged conductor is connected to the Earth?
Charge neutralised by electrons transfer between the conductor and the Earth.
What is the magnitude of electrical force between two point charges?
(aka Coulomb’s law)
What do the letters represent in this equation?
What is the permittivity of free space?
A measure of the ablility of a vacuum to allow an electric field to pass through it.
For subatomic particles, which force is stronger gravity or electrostatic?
Electrostatic
Electric field lines go from what type of charge to what type of charge?
From positive to negative.
Draw an uniform electrical field.
Draw two radial electric fields one around a negative charge and the on around a positive charge.
Define electrical field strength.
Force per unit charge exerted on a test charge within the field.
What is the magnitude of electrical field strength in a uniform field?
What do the letters represent in this equation?
What is the magnitude of electrical field strength in a radial field?
What do the letters represent in this equation?
What is the work done moving a charge between a pair of parallel plates?
What do the letters represent in this equation?
What is the trajectory of a particle entering a uniform field at right angles?
Parabolic.
(Like projectile motion)
Define electrical potential.
The work done per unit charge, moving a test charge from infinity to a specific point.
Define electrical potential difference.
The difference in the electrical potential at two points in an electric field.
What is the work done when moving a charge in an electric field?
Is work done when moving a charge along an equipotential surface?
No.
(Since the potential difference is zero)
Draw an uniform electric field with equipotentials.
