# Faraday's induced emf equation

cblair
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Why is there negative sign in Faraday’s induced emf equation?

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167Forum Coordinator"Faraday’s laws of electromagnetic induction states that when a coil of wire is placed in a changing magnetic field (B) an EMF (E) is induced in the coil and the induced EMF is proportional to the rate of change of flux linkage with the coil (dφ/dt).

E = N(- dφ/dt)

Meaning of the minus sign in Faraday’s law is explained by Lenz’s law which says if the B field changes, the voltage induced in the coil will try to drive a current that produces a B-field which opposes the change(in primary B field)."

102Forum CoordinatorThanks, Could you please elaborate more on what does the negative sign signify?

167Forum Coordinator102Forum Coordinator1MemberI need to use some verification sample in ANSYS to calculate generated voltage based on Faraday laws. Which verification sample did I select for ANSYS?

6MemberThis PDF - Understanding and using the minus sign in Faraday's law, explains everything you need - the negative sign in faraday's law, Lenz's law, and application of the negative sign in Faraday's law. Additionally, you can also read Engineering Electromagnetics by William Hayt - this would give you an excellent insight into the world of electromagnetics and its application in major science.