Unit 1 topic 3- Electrical circuits Flashcards
Explain the concept of charge and how it can be classified.
Charge is the absence (deficiency) or excess of electrons. If it is the same as an electron it is negative, and the opposite to an electron it is called positive.
What is electric charge
A physical property of an object that causes it to experience a force when placed in an electric field
Insulators
Do not allow charge to flow easily, have limited or no free electrons
conductors
allow charge to flow, have free electrons (not tightly bound to nucleus)
semi-conductors
allow charge to flow sometimes (electrons are tightly bound to the nucleus unless they are given energy from outside source)
Law of conservation of electric charge
the total electric charge of an isolated system remains constant, regardless of changes within the system (i.e charge cannot be created nor destroyed)
Law of electrostatic attraction
opposites attract, likes repel
electric current
the rate of movement of electric charge carriers from one part of a conductor to another
unit for current
I
unit for charge
C
What is conventional current
Conventional current is in the opposite direction to electron flow
How is a voltage created
A voltage is created by separating positive and negative charges
Electromotive force (NOT A FORCE)
a difference in potential that tends to give rise to an electric current
Electrical potential difference
The change in potential energy per unit charge between two defined points in a circuit
Resistance
the ratio of voltage to current in a material
What does the resistance of a wire depend on
length, material, diameter, temperature
What happens to resistivity as length increases
R increases
what happens to resistivity if diameter increases
R decreases
ohmic resistor
a resistor that behaves according to ohms law
non ohmic resistor
a resistor that does not behave according to ohms law
in series
one after the other (on same path)
what current do resistors in series experience
resistors in series experience the same current
in parallel
on top of each other
what potential difference do resistors in parallel experience
resistors in parallel all have the same potential difference
