# Electricity from Magnetism

## Key Questions

When a moving conductor(like copper or iron) placed in the magnetic field,then an emf is induced in an electrical conductor.
This is called electromagnetic induction.

#### Explanation:

$$Can we produce electricity by magnetic field?


In order to drive the current , an application of voltage(emf)
is compulsory. Without an application of voltage(emf),
there is no electricity.

Conclusion: In order to drive current,application of voltage is needy.

Where we get voltage?

How can we apply a moving force to very small electrons?

$$         There are number of methods  to produce voltage(emf).
An ****electromagnetic induction**** is one of the greatest method used
to produce electricity.


Principle:
When a moving conductor(like copper or iron) placed in the magnetic field , then magnetic lines cuts the moving conductor.
If magnetic lines cuts the moving conductor ,
then emf(voltage) is induced in the conductor which further drives
the current when closed circuit is provided.

$\mathmr{and}$

$$When a stationary conductor is placed in between moving magnets
, an emf is induced in the conductor.


Electromagnetic induction is the generation of an electric field due to a varying magnetic field. It depends on several factors.

#### Explanation:

As most of us would know, the electric field in a material medium is dependent on the dielectric constant of the medium. Thus, the net electric field in the region shall depend on the properties of the medium itself.

Other than that, quantitatively the phenomena of electromagnetic induction is given by the Faraday's law as,

 E = - (dphi""_B)/dt where phi""_B is the magnetic flux and E is the emf generated.

The generation of emf is due to the generation of the electric field.

In terms of Maxwell's equations, the phenomena can be described accurately as,

$\nabla$ X E = $- \frac{\partial B}{\partial t}$ where B is the magnetic field.

Now that we know that flux change induces an electric field, it should be a matter of common sense that, the flux can be changed in several ways, by changing the magnitude of the field, the changing the area or my changing the orientation of the field with respect to the area.

The negative sign indicates that, emf is so produced that it tends to oppose the change in the field that produced it which is described by the Lenz law in accordance with the law of conservation of energy.

If flux change occurs within a closed circuit, the emf so produced shall produce a current in the circuit.

In absence of a closed circuit, the electric field (and the emf) is still there.

• If you mean Fleming's right hand rule, then here is my go,

It's simply a shortcut for knowing the direction of induced current in a conductor(during electromagnetic induction) .

Thumb represents motion

First finger represents magnetic field direction(into paper or out of paper)

Second finger represents the current induced.

Most of the time we have the motion of the conductor and the direction of the B-field, and we're looking for the current