how does an atom become charged
when it had an unequal number of protons and electrons in the atom
how does attraction work
like charges repel each other, whilst opposite charges attract each other
CHARGE
symbol = Q
unit = coulumb (C)
what is the elementary charge?
its the charge of 1 electron.
1.602×10⁻¹⁹ C.
what is the Faraday constant(F)
its the charge of 1 mole of electron.
F = 9.648 x 10’4 C.mol-1
avagadro constant
1 mole of electrons (which is 6.022×10^{23} electrons)
what is an electric field
Region where a charge experiences a force (where it can push or pull other charges).
Mapped using electric field lines.
direction of the field lines
- A positive charge sends out arrows pointing away (because it pushes other positives away).
- A negative charge sends out arrows pointing in (because it pulls positives in)
electric field formula
E=F/q
what is an electrical potential energy
how much energy a charge has at a point.
its also similar to gravitational energy
VOLTAGE
work done moving 1 coulomb of charge between two points. (amount of energy needed to move 1 coulomb of charge from one point to another).
unit= volt (v)
Potential energy formula
Work (W, in joule, J) = coulomb (Q) of charge moved through a potential difference (V): W = QV.
1 volt, is 1 joule per coulumb of charge
cations
positively charged ions (e.g., Na⁺).
anions
negatively charged ions (e.g., Cl⁻).
units conversion
1V = 1000 mV
1A = 1000 mA
conducters in biology - cations
Positively charged ions move towards a region
of negative potential (a cathode)
conducters in biology - anions
Negatively charged ions move towards a region
of positive potential (an anode)
conducters
they allow electrons and ions flow - so charge flows through them which means they conduct electricity
biological conducters
Electrolytes are compounds whose aqueous solutions conduct
electricity
insulators
they may have electrons and ions but they are locked in a place, so charge cant flow through - so no electricity
CURRENT
symbol = I
unit = amps (A)
the rate at which a charge passes a point in a closed circuit (1 amp = 1 coulomb per second) - I = Q/t
RESISTANCE
symbol = R
unit = ohms
defined as opposition to current flow (it doesnt stop charge, it just slows it down)
CONDUCTANCE
symbol = G
unit = siemens (S)
the ease with which a charge flows through a conductor
ohms law
V = IR
