Charge and Current

What is current and formula?

rate of flow of charge,

I = Q/t

What is a coulomb?

unit of charge

How to find the number of electrons passing a point?

find the charge, then divide by elementary charge

How is charge carried in a metal?

a lattice of positive ions, surrounded by free electrons which move

How is charge carried in electrolytes?

using electrodes, positive and negative ions are attracted to electrodes causing a current

What is conventional current and electron flow?

conventional current - flow of charge from positive to negative terminal

electron flow - flow of electrons from negative to positive

What is Kirchoff’s first law?

conservation of charge - for any point, the sim of current into it is equal to the sum of currents out

What is mean drift velocity?

average velocity of electrons as they travel down the wire as they collide with positive metal ions

What is the mean drift velocity equation?

I = nAve

(n is number density)

What is number density n?

number of free electrons per unit volume

Which materials have high number density?

conductors have high n

insulators have very low n

semiconductors have in the middle