1.9- Electric Current, Charge, Potential Difference and Electromotive Force Flashcards
How do conductors conduct electricity?
They have a supply of charge carriers ( electrons ) which are delocalised and can carry current from one end of a structure to the other
What makes a good insulator?
A material that has no free electrons, ( all are used up in ionic/covalent bonding)
How do electrons act in a crystal lattice ?
They’re in a state of rapid motion, typically in completely random directions
What happens when a potential difference is applied across a metal lattice?
There is a net drift of electrons to the region of higher potential, they gain kinetic energy
Why do we observe an increase in heat when p.d is applied across a conductor?
Collisions between the electrons cause them to give up some of their kinetic energy to the atoms, this causes the atoms to vibrate more violently about their mean positions.
How is electrical resistance explained?
By collisions between the delocalised electrons and vibrating atoms
What happens after an electrons collision?
They accelerate again. Their net acceleration is 0 as the collisions are so frequent. But there is a drift of negative charge towards the positive potential ( this constitutes as the electric current )
Write the equation for charge
Q=IT
Q= C
I= A
T= S
What is the charge of one electron.?
-1.6X10^-19
State the equation for number of electrons
Number of electrons = Total Charge/ Charge of single electron (1.6X10^-19)
Definition of the EMF of a battery
The energy converted into electrical energy when 1C passes through it
Write the equation for EMF
E=W/Q
E= e.m.f in volts
W= energy converted into joules
Q= Charge
Definition of a volt
A joule per coulomb( Or a watt per ampere)
Equation between Charge, potential difference and energy ( in joules )
W=QE
Joules= Coulombs X volts
How does E.M.F differ from P.D
E.M.F. Applies to a source supplying electrical energy
P.D refers to the conversion of energy in a circuit
