DC Principles Flashcards
What are the names and units for; Charge Current Voltage
Charge (q) - coulomb (C) Current (i) - Ampere (A) Voltage (v) - Volt (V)
A current is a….
Coulomb per second
A volt is a…
Joule per coulomb
What’s the charge on an electron?
-1.6x10^-19C
Current(i) = ?
i(t)=dq(t)/dt = Charge/Time
Total charge through a conductor q(t) = ?
q(t) = t(integral)t0 i(t)dt + q(t0)
Voltage is…
The energy transferred per unit charge that flows through the element
A watt is a…
Joule per second
Power =
Voltage x Current
If energy is ____ it is positive but if it is supplied it is ____
If energy is absorbed it is positive but if it is supplied it is negative
Equation to calculate the power delivered to a circuit element between time instants t1 and t2
w = t2(intergral)t1 p(t)dt
The net current entering and leaving a node is?
0
State Kirchoff’s Voltage Law
The algebraic sum of the voltages equals zero for any closed path (loop) in an electrical circuit
In conductors, the voltage between any 2 points of an ____ conductor is ____ regardless of the current
In conductors, the voltage between any 2 points of an ideal conductor is zero regardless of the current
When 2 points are connected by an ideal conductor they are ____ together
Shorted
There is an open circuit between two parts of the circuit when?
There are no conductors or other circuit elements connected between 2 parts of a circuit
Dependant voltage sources (also knows as ____ ____ ____) are represented by?
(Controlled voltage sources) Diamond shapes
Resistance = ? and ?
R=V/I and R=(pL)/A
Voltage is ____ to ____ in an ideal resistor
Voltage is proportional to current in an ideal resistor
Typical values of resistivity for Conductors = conductors = Insulators =
Conductors = 10^-8 conductors = 0.1 Insulators = 10^21 (‘infinity’)
Conductance is? and so (Symbol, equation and unit)
G which is 1/R and so Ohms^-1 and so i=Gv
Energy = ? (for a battery)
Q.v
Q = ?
i.T
Energy = ? (2 obvious ones)
mgh and 1/2mv^2
Energy density = ?
Energy (J) / Mass (kg)
Conductances in series and parallel is…?
Opposite to resistance
Voltage divider?
V1 = R1 x i = R1 / (R1+R2+R3) x Vtotal
Fraction of voltage is ratio of…?
Given resistance / total resistance
Fraction of current is ratio of…?
Other resistance / total resistance
For current division - i1 = ? and i2 = ?
i1 = v/R1 = R2/R1+R2 x itotal and i2 = v/R2 = R1/R1+R2 x itotal
The current flowing from node n toward node k is given by…?
(Vn-Vk)/Rx
Avoid writing ____ equations for loops that include ____ sources
Avoid writing KVL equations for loops that include current sources
To ‘zero’ a voltage source you…
Replace it with an short circuit
To ‘zero’ a current source you…
Replace it with an open circuit
The load resistance that maximises the power delivered to the load from a two-terminal circuit is equal to…?
The Thévenin resistance (also called the output resistance) of the circuit
Maximum power results in…?
Plmax = Vt^2/4Rt
iL = ?
iL = Vt/(Rt+RL)
Electrons with never go through a wire with ____, it will always go the ____ ____
Electrons will never go through a wire with resistance, it will always go the other way
Anything in parallel with a empty wire makes…?
0V
The total response is…
The sum of the responses to each of the independent sources acting individually
A resistance that obeys Ohm’s law is…?
Linear
What only applies to linear circuits?
Superposition
What is used to measure unknown resistances?
The Wheatstone bridge
When is the Wheatstone bridge balanced?
when ig = 0 and Vab = 0
For the Wheatstone bridge, Rx = ?
Rx = (R2/R1)R3
