Question

What does a time-varying magnetic field yield?

Answer 1

1. A time-varying magnetic field yield an electric field.
   
2. According to the first law of Faraday, whenever a conductor is placed in a varying magnetic field, an electromotive force is induced. If the conductor circuit is closed, a current is induced, which is called induced current.
3. The induced emf in a coil is equal to the rate of change of flux linkage.
   $\mathrm{\epsilon }=-\mathrm{N}\frac{∆\mathrm{\varphi }}{∆\mathrm{t}}$
   where, $\mathrm{\epsilon }$is the electromotive force, $∆\mathrm{\varphi }$ is the change in magnetic flux, $∆\mathrm{t}$ is the change in time, and N is the number of turns.
4. We can conclude from the above statements, that a varying magnetic field produces an electric field.
5. The negative sign shows that the magnetic field's direction and the induced emf's direction have opposite signs.
6. The direction of induced emf is given by Lenz law.
7. Lenz law: It states that the direction of an induced current is always such as to oppose the change in the circuit or the magnetic field that produces it.