# Electromagnetic Field

When an electric charge moves in space electromagnetic field generated. The electromagnetic field is the combination of a magnetic field and an electric field. The electromagnetic field can be defined as light since it propagates at the speed of light. Maxwellâ€™s law and Lorentz force law describe the way current and charges interact with the electromagnetic field. An electromagnetic field propagates in a waveform. First electric and magnetic field are generated by moving electric charges then electric and magnetic field collides with each other. As a result, the electric field and magnetic field create forces on electric charges hence the electric charge moves in space.

Space or region which experiences the force due to both electric charge and magnetic charge is known as the Electromagnetic field. The scalar property of the electromagnetic field is the only magnitude. The vector properties of an electromagnetic field are direction and magnitude.

Electromagnetic Field

## Equations:

There are four main equations in electromagnetic theory.

i) Gauss Law:

It describes the electric field around a point charge.

Total flux line in any area is equal to $$\frac{q}{\epsilon }$$

Gauss Law = $$\int E.dA=\frac{q}{\epsilon }$$

ii) Gauss law for magnetism:

Total of magnetic flux is zero.

Hence, $$\int B.dA=0$$

A change of electric field causes a change in the rate of change of flux.

Hence, $$\int E.dl=-\frac{\mathrm{d} }{\mathrm{d} t}(\int B.dA)$$

iv) Ampere-Maxwell Law:

$$\int B.dl=\mu (I+\frac{\mathrm{d} }{\mathrm{d} t}(\epsilon \int E.dA))$$

### Properties of Electromagnetic Field:

Maxwell equations, Ampere-Maxwell law state that if we change in a magnetic field an electric field is generated. This is the principle in which electric generators work. But Ampereâ€™s law states that if we change in electric field magnetic field is generated. So here we can see reciprocal behaviour of the electric and magnetic field.

Electromagnetic field sources consist of two types of charges positive and negative. Sometimes the electromagnetic field and gravitational field ripple each other.

### Applications:

#### i) Household Appliances:

There are many home appliances in the household application in which electromagnetic field principle works. There are so many things which work on electromagnetism. Lights, fans, kitchen appliances, conditioning systems all work on the principle of electromagnetism. The alarming system works based on electromagnetism principle. Home security system, electric speaker all work on the principle of electromagnetism.

#### ii) Industrial Applications:

Most of the used instruments and machines in the industry are based on the principle of electromagnetism. One of the most used machine in an industrial area is a generator or motor which is the primary source of power in the industry. This generator or motor converts the mechanical energy to electrical energy and this energy is supplied to the main power system by IC engines. This motor or generator works on the principle of electromagnetism.

Magnetic levitation trains also use the concept of electromagnetism. These magnetic levitation trains run over the line using the principle of magnets such as EMS and EDS.

#### iii) Communication System:

In the case of mobile phones or any communication system sound energy is converted to electromagnetic energy. Now the radio transmitters transfer the electromagnetic energy to the receiver. At the receiver end, the electromagnetic energy again converted to sound energy.

#### iv) Medical system:

Most of the advanced medical equipment is based on the principle of electromagnetism. Medical equipment such as hyperthermia treatments for cancer, magnetic resonance imaging and implants work on the principle of electromagnetism. A most common medical service MRI scan can scan the whole body of a human in a minute. This is also based on electromagnetism. Nervous disorders, diabetes, spinal cord injuries, ulcers, asthma these type of treatments done by electromagnetic radiation. X-ray equipment, scanners all are the most common devices useful in medical services. These devices are based on electromagnetism.

High flux levels of electromagnetic radiation cause critical health effects in people. Most common health disease is sunburn which causes a lot of skin cancers all over the world.

Q.1 Describe the Electromagnetic field.

Answer:Â  Electromagnetic fields are mainly invisible force fields where a flow of energy is present. It is a combination of electric field and magnetic field.

Q.2: Can we create magnetic waves?

Answer: Yes we can create electromagnetic waves by using magnets but it is not possible to create magnetic waves without an electric field.

Q.3: What could happen when someone is exposed to EMF?

Answer: It can lead to dizziness, seeing light flashes and even one can feel pain through nerves. The electromagnetic field is harmful to human health. In daily life, everybody experience a greater or lesser degree of EMF.

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