Positive and Negative are the two types of charge: $+ve$ and $-ve$
Neutral - neutrinos, antineutrinos, neutrons i.e. fundamental particles that have no charge
atoms by definition are an uncharged species
Charge, like mass is a property of matter
An object of charge possesses an electric field around it which:
extends to infinity
results in other objects of charge experiencing an electric force when placed in the field
has an electric field which decreases with distance from the object
this force may be attraction or propulsion
If electrons are redistributed on an object to produce regions of different charge i.e. an electric dipole, then this is charging by induction. - the separation of charge is temporary and will reverse once the inducing charge is removed
If electrons are physically transferred then the loss/gain of charge is not temporary - this is charging by conduction
Electric Field Diagram
It is assumed that charge is uniformly distributed around a charged object
Field lines are evenly distributed around objection
minimum of four field lines
Must be an arrow going the right direction
Coulomb's Law
$Fe$ - the force of an electric field
It decreases inversely proportional to the square of the distance
$$Fe=\frac{k \space q_{1}q_2}{r^2}$$
$k$ is the constant of proportionality - $9.00\times10^9$
$q_{1}...$ are the two charged objects (in $c$ - Coulombs , which measure charge)
$r (d)$ is the distance between the two objects
Two point charges of $7.4mC$ and $6.4mC$ are $65.4cm$ apart. What is the force acting between them.
it is $1.00N$ $24.6=\frac{x}{5.8081}$
Electric Circuits
Current is a flow of at least one electron
Conventional Current is the flow of $+ve$ charge, i.e. current
E circuits transform electrical energy into other forms of useful energy - thermal, electromagnetic/photonic
Minimum components for a circuit
Power pack i.e. source of energy/potential difference e.g. battery
Wire - conducting material made of a conductor
Devices/component/resistors
Potential Difference
When charge moves from one position to another, work is done on the change i.e. they have changed in their electric potential energy
$W=\Delta E$
$V=\frac{W}{q}$
$V=$ potential difference/voltage ($V$)
$W=$ work done (change in $Ep$) ($J$)
$q=$ charge ($C$)
Current
The amount of charge which flows past a given point in a given unit of time
$I=\frac{q}{\Delta t}$
$I=$ current in amperes ($A$)
$q=$ charge ($C$)
$\Delta t=$ time interval ($s$)
3.01c 4.05m = 243s
$I=3.01/243$
The PRAC!
Series
Current is the same in every part of a series circuit
If more components (that is, resistors) are added, the effective current is reduced, but will still be the same everywhere
$I_{tot}=I_1=I_2=I_3$
$V=IR$
For a single component in series with the energy source, $V=emf$
If more components are added in series then the sum of their individual drops in voltage add up to the sum of the voltage drops across all of them
$V_{tot}=V_1+V_2+V_3$
Parallel
Current is divided among components in different branches
$I_{tot}=I_1+I_2+I_3$
Voltage is the same in each branch
$V_{tot}=V_1=V_2=V_3$
Ohm's law and resistance
Resistance is the measure of the difficulty with which charge moves through a medium ($\Omega$)