Equations · Physics
Faraday's law of induction
A changing magnetic field creates a circulating electric field.
∇ × E = −∂B/∂t
Aethel says
the curl of E equals negative the partial derivative of B with respect to t
What it says
The curl of the electric field, how much it swirls around a point, equals minus the rate of change of the magnetic field. The minus sign is Lenz's law: the induced effect opposes the change.
Generators and transformers work because of it.
Symbol by symbol
| Symbol | Say it | Means |
|---|---|---|
| ∇ × | the curl of | how much a field circulates around a point |
| E | E | the electric field |
| ∂B/∂t | the partial derivative of B with respect to t | how fast the magnetic field changes |
Where you meet it
Electromagnetism and electrical engineering.
Questions
How do you say Faraday's law of induction out loud?
∇ × E = −∂B/∂t is read: “the curl of E equals negative the partial derivative of B with respect to t.” That is exactly what Aethel says when it meets the formula in a book.
What does ∇ × mean in Faraday's law of induction?
∇ × (said “the curl of”) is how much a field circulates around a point.
What does E mean in Faraday's law of induction?
E (said “E”) is the electric field.
Can I listen to the equations in my own textbook like this?
Yes. Upload a PDF, EPUB or text file and Aethel reads it aloud with every equation spoken as maths, the way it reads this one, and highlights each sentence as it goes. You can start free.