Flashcards
mean drift velocity
Cards in this deck (13)
- 1what is graphenepure carbon arranged in thin sheets one atom thick. its very strong and flexible. it has a large number of electrons, and the number density of it is greater than that of copper, making it an excellent conductor
- 2what is the number densitynumber of free charge carriers per cubic metre of material. the higher the number density the better the conductor
- 3name two insulatorswax, rubber etc
- 4name two semiconductorssilicon, germanium
- 5name two conductorslead, zinc etc
- 6what is number density measured inn/m*-3
- 7what are microprocessors made of and the disadvantagessilicon, and they can get very hot when a current passes through them, so computers need a very good cooling system
- 8name an equation for electric current that involves the elementary chargecurrent in conductor = cross sectional area m*2 x elementary charge x number density x mean drift velocity
- 9what is mean drift velocityaverage velocity attained by charged particles
- 10how does the mean drift velocity change when the cross sectional are of a wire changesthe narrower the wire, the greater the drift velocity must be in order for the current to stay the same
- 11how do you derive the equation I = A n e vI = Q / t. in a wire there are a specific number of charge carriers per unit volume (the number density, n) the V of material = L A, so the number of electrons = n L A, so Q = n A L e. the t for the electrons to pass a certain point = L / v. so I = n L A e / L / v, the v can move to the top to give I = n L A e / L, the two ls cancel out to give I = A n e v
- 12name all the equations used to derive I = A n e vI = Q / t
V = A L
number of electrons = n V
total charge = number of electrons x e
time taken for electrons to pass a given point = L / v - 13what do each of these symbols represent in the derivation of I = A n e v I, Q, t, V, A, L, n, v, e,I = current, Q = charge, t = time, V = volume, A = cross sectional area, L = length, n = number density, v = mean drift velocity, e = elementary charge
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- physics A level (M4 Chapter 8 current and charge) Flashcards on mean drift velocity, created by lizabeth rawson on 16/09/2020.
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