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Inductance
20 questions By Tony R. Kuphaldt
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Question 19 of 20
Electrical inductance has a close mechanical analogy: inertia. Explain what mechanical “inertia” is, and how the quantities of velocity and force applied to an object with mass are respectively analogous to current and voltage applied to an inductance.
Reveal answerAs an object is subjected to a constant, unbalanced force, its velocity changes at a linear rate:
F = m dv dtWhere,
F = Net force applied to object
m = Mass of object
v = Velocity of object
t = Time
In a similar manner, a pure inductance experiencing a constant voltage will exhibit a constant rate of current change over time:
e = L di dtNotes:Explain to your students how the similarities between inertia and inductance are so close, that inductors can be used to electrically model mechanical inertia.
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Question 20 of 20
∫f(x) dx Calculus alert!
Inductors store energy in the form of a magnetic field. We may calculate the energy stored in an inductance by integrating the product of inductor voltage and inductor current (P = IV) over time, since we know that power is the rate at which work (W) is done, and the amount of work done to an inductor taking it from zero current to some non-zero amount of current constitutes energy stored (U):P = dW dtdW = P dt U = W = ⌠ ⌡ P dt Find a way to substitute inductance (L) and current (I) into the integrand so you may integrate to find an equation describing the amount of energy stored in an inductor for any given inductance and current values.
Reveal answerU = 1 2LI2 Notes:The integration required to obtain the answer is commonly found in calculus-based physics textbooks, and is an easy (power rule) integration.
