D.2 Electric and Magnetic Fields Flashcards
Charge (Q or q)
Coulomb (C)
Conservation of charge
Charge cannot be created or destroyed
Coulomb’s Law
Force between two point charges is proportional to the product of their charges (q1 and q2) and inversely proportional to the square of their separation (r)
Point charge
A charged object that does not take up any space - it is infinitely small
Objects are point charges when…
the distance between them is large compared to the physical size of the objects and they experience the same size force.
Charging by friction
Electrons are transferred from one object to another, gain equal but opposite charges. Charge separation by friction
Do insulators or conductors become charged by friction?
Insulations as in conductors, electrons move to keep the object neutral
Charging by contact
Uncharged objects become charged when they come into contact with charged objects. Gain the same charge as the charged object
Do insulators or conductors become charged by contact?
Conductors as electrons can move around easily. They cannot do this in insulators.
Grounding
Earth is a conductor and because of its size, it is an infinite store of charge. If a charged object is connected to the Earth via a conductor, electrons flow to or from the earth to discharge it. It gains opposite charge to the charge rod.
Electric field
A region of space where a charged object experiences a force due to its charge
What do field lines show?
Closer the lines, stronger the field.
The direction a force would act on a positive charge placed at a point.
Electric field strength
Force per unit charge experienced by a small positive charge placed in the field.
How is a uniform electric field created?
Two oppositely charged parallel plates
