5. Electricity and magnetism Flashcards
one coulomb
the charge transported by a current of one ampere in one second
electric field
a region where a charged object experiences a force.
electric field strength
the force per unit charge experienced by a small positive point charge placed at that point.
coulomb’s law
the force of repulsion between two charged objects is proportional to the product of the charges and inversely proportional to the square of the separation.
current
the rate of flow of charge.
direct current
current that flows in just one direction.
Potential difference
the energy transferred from one coulomb of charge moving between two points in a circuit.
Electromotive force (EMF)
the energy transferred to electrical energy per coulomb of charge.
electron volt
the energy transferred to an electron when it moves through a potential difference of one volt = 1.6*10-19 J
Kirchoff’s first law =
the sum of the current into a junction equals the sum of the currents away from a junction.
Kirchoff’s second law =
in a complete circuit loop, the sum of the emfs in the loop is equal to the sum of the potential differences in a loop.
Ohm’s law =
the pd across a metallic conductor is directly proportional to the current in the conductor providing that the physical conditions of the conductor do not change.
Primary cell =
an electric cell that produces current by an irreversible chemical reaction.
Secondary cell =
a rechargeable electric cell that converts chemical energy into electrical energy by a reversible chemical reaction.
The capacity of a cell =
a measure of the ability of a a cell to release charge = the constant (ish) current * the time it can supply this for.
