Electric Circuits Flashcards
What is the electric current (I)
The rate of flow of charged particles
What is the equation for the electric current?
I = ∆Q/ ∆t
What is voltage?
1 volt -> potential difference between two points when 1 joule of work is done to move a charge of 1 coulomb.
What’s the equation for voltage?
V = W/ Q
what is the electric current’s SI unit
Ampere
what is the solid definition of Ampere (A)?
The current flowing in two parallel wires 1m apart in a vacuum such that there is an attractive force of 2 * 10^7 N per meter length between them
what is 1 Ampere equal to
1 ampere -> 1 Coulomb of charge passing a point in 1 second
In what direction does the conventional charge flow?
From positive to negative
In what direction do the electrons flow in a circuit?
From negative to positive
What device do we use to measure the current?
The ammeter
how do we use the ammeter
It goes in series with the other parts of the circuit
what is the mass of an electron?
9.1 * 10^-31 kg
what is elementary charge equal to?
1.6 * 10^ -19 Coulomb
What is the definition of a coulomb
The charge that flows past a point in 1 second when there is a current of 1 amp
What is the equation for the charge?
∆Q = I * ∆t
What is Kirchhoff’s 1st Law?
at any point in an electrical circuit, the sum of currents into that point is equal to the sum of currents out, electrical charge is conserved.
what is the cross-sectional area equal to?
A = π d^2 / 4
what is the volume equal to
V = Length * Area
what is the equation for the no. of free electrons
volume * charge density | nL A
Total charge free to move =
= nLAe
Time for charge to leave this bit of wire =
= length / drift velocity
Another derivation of I = Q / T is
I = n A v e
what is the velocity equal to
v = n A e / I
what is the electro-motive force
EMF is the energy per unit charge transferred from chemical energy into electrical energy
