principle of charge conservation
during any process the algebraic sum of all the electric charges in any closed system is constant
coulomb’s law
the magnitude of the electrostatic force exerted by one point charge on another point charge is directly proportional to the magnitudes of the charges and inversely proportional to the square of the distance between them
newton’s universal law of gravitation
states that every object in the universe attracts every other object with a force.
coulomb’s vs. newton’s
similarities:
- both laws describe inverse square relationships meaning the force decreases as the square of the distance between the two objects increases
- both equations have a constant that is specific to the force they describe
differences:
- the electrostatic force between charges can be attractive or repulsive
- the gravitational force between masses is always attractive
electric field
electricity that exists at a point is the electrostatic force experienced by a small positive test charge placed at that point divided by the charge itself
electrical potential energy
capacity to do work due to an object’s position in an electric field. charged particles can accelerate towards each other
electrical potential
the electrical potential energy divided by the charge itself
voltage
states that every object in the universe attracts every other object with a force. Voltage is the “push” that makes electric charges flow through a circuit.
conventional current
the hypothetical flow of ‘+’ charges that would have the same effect in the circuit as the movement of ‘-‘ charges that does occur
direct current
if charges move around a circuit in the same direction at all times, the kind produced by batteries
alternating current
when the charges move first one way and then the opposite way, changing direction from moment to moment
Ohm’s law
the electric current I is directly proportional to the voltage V
resistance
the ratio of the voltage V applied across a piece of material to the current I though the material
resistivity
an inherent property of a material, inherent in the same sense that density is an inherent property
electric power
when electric charge flows from point A to point B in a circuit, leading to a current I, and the voltage between the points is V, the electric power associated with this current and voltage is P=IV
kirchhoff’s junction rule
an application of the law of conservation of electric charge to the electric current in a circuit. the sum of the magnitudes of the currents directed into a junction equals the sum of the magnitudes of the currents directed out of the junction
kirchhoff’s loop rule
an application of the principle of conservation of energy to the electric potential that exists at various places in a circuit. around any closed-circuit loop, the sum of the potential drops equals the sum of the potential rises
