Mod 4: charge and current Flashcards
(34 cards)
What is the structure of a metal
A lattice of positive ions surrounded by delocalised electrons
How does solid metal conduct electricity
(Structure) one side of the metal is made to be positive and the other is made to be negative so the electrons will be attracted to the positive so current will flow through the structure
How does NaCl solution conduct electricity
The electrolyte NaCl contains +ve and -ve ions therefore the electrolyte will split into Na+ cations and Cl- anions so when a pair of electrodes are place in the solution the cations will be attracted to the cathode and the anions will be attracted to the anode. This produces an electrical current
Which is the +ve and _ve electrode
Anode= positive
Cathode= negative
What is conventional current
The flow of positive charge that moves in the opposite direction of electrons (+ve- -ve)
Describe the electron flow in a metal
It is in the opposite direction of conventional current
What is Kirchohoff’s first law
For any point in an electrical circuit the sum of the currents in to that point is equal to the sum of currents out of that point. This law is a consequence of conservation of charge as charge can not be created or destroyed.
What is mean drift velocity
The average rate of change of displacement of the charge carriers in a substance
Why does mean drift velocity happen
When e- move through a metal they frequently collide with the positive metal ions resulting in the random movement.
What does the number density n represent
The number of charge carriers per unit m^3
Describe the number density n in conductors vs insulators
- the value n is much higher in conductors than in insulators therefore the e- in insulators must travel faster in order to carry the same current than the n in conductors
What is the net charge on a particle a multiple of
It is the multiple of e (elementary charge)
How was the conventional current defined as
A flow of positive charge
What is n the number density
The number of charge carriers per m^3
What is drift velocity
The average rate of change of displacement of the charge carriers in a substance
How do electrons travel
-ve to +ve
Which electrical quantity has the s.i unit of amperes per second
Charge
What is elementary charge
The smallest unit that charge come in.
What is the specific word to describe charge as a multiple of e
Quantised
How many volts does 1JC^-1 equal to
1 V
What is the energy transferred to a charged particle that is accelerated by a p.d equal to
The work done on the particle
: W=VQ.
W=Ve
What is the unit for n in I=AneV
Metre^-3
What is the n in perfect insulators and real insulators
0
Real insulators have very few n
Is ionic crystals a conductor or an insulator
Insulator however once molten the liquid will conduct
