Topic 5 - Inductors Flashcards
Parts 6 & 7 of the textbook (19 cards)
What is an inductor?
Circuit element that stores energy in its magnetic field, whereas capacitors store energy in their electric field.
What does an inductor consist of? What properties do all conductors have?
A coil of conducting wire. Any conductor of current has inductive properties.
Relationship between voltage and current through an inductor?
If current is passed through an inductor, the voltage across it is proportional to the rate of change in current over time.
What letter is inductance described as?
L
What is inductance? What is it measured in?
The property in which an inductor opposes the change of current flowing through it. Measured in Henrys (H).
Are inductors active or passive?
Passive. Acts same as resistors and capacitors.
How do you find current through an inductor? Thing to note when compared with RC circuits?
Where i(t0) is the current at time to. Note that the main variable we are interested in with RL circuits is the current, while in RC circuits, we were interested in the voltage.
Equation for power delivered to an inductor?
Equation for the energy stored in the magnetic field in the inductor?
Integrate the electric charge equation.
What would happen to an inductor if the current was constant?
Voltage = 0. Therefore, the in ductor would act as a short circuit.
So in DC current (and steady state), an inductor acts as a short circuit.
How do real inductors function?
Like ideal capacitors, ideal inductors donโt dissipate energy. However, real inductors have a small winding resistance (Rw) in series, and a small winding capacitance (Cw) in parallel, leading to a slow loss of energy.
What happens with inductors in series?
Inductances are added together.
Characteristics of basic elements (Not a Q)
What happens with inductors in parallel?
Same as resistors.
Formula for the natural response of an RL circuit?
Where Io is the initial current.
What is tau (๐) in RL circuits?
It represents the time constant, which is the time required for the circuitโs current to decay to 1/3 (or 36.8%) of itโs initial value. It is equal to Inductance/Resistance (L/R)
Important convention when finding tau (๐)?
Remember tau (๐) is the time constant, and thus, has units (s).
When can we assume that an inductor is fully discharged?
After 5 taus (๐).
What is the formula for step response of RL circuits? Also, when is tau measured?
Tau is measured after t0.
