Determinant of the EMF of self-induction, arising in a coil with an inductance of 25 milligrams, if, 75 ms

| January 13, 2021 | education

Determinant of the EMF of self-induction, arising in a coil with an inductance of 25 milligrams, if, 75 ms after the circuit is closed, a current of 3.75 A is established in it. What is the physical meaning of the sign of the EMF of self-induction?

L = 25 mH = 0.025 H.
t = 75 ms = 0.075 s.
ΔI = 3.75 A.
EMF -?
According to Faraday’s law of electromagnetic induction, the EMF of induction is directly proportional to the rate of change of the magnetic flux EMF = – ΔF / t.
The “-” sign indicates the direction of the induction current, which is determined by the Lenz rule.
The change in the magnetic flux of the coil ΔФ is expressed by the formula: ΔФ = Δ (L * I) = L * ΔI, where L is the inductance of the coil, I is the current strength.
The formula of Faraday’s law will take the form: EMF = – L * ΔI / t.
EMF = 0.025 H * 3.75 A = 1.25 V.
Answer: during self-induction, an EMF current of 1.25 V appears in the coil.



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