Basic Concept of Fields

We as a student of engineering or science deals with various fields, some common field among them are as follows.

• Gravitational field
• Electrical field
• Magnetic field

In general a field can be a space or location, where some special significance or influence can be sensed or felt, which depends upon various factors, like the type of fields.

🔶How to feel Gravitational Field ?

For growing visual idea consider gravitational field first. As we all know earth attracts any object towards it when thrown above , it can only attract the object within a certain limit of height, beyond that it losses its strength so called gravitational strength.

So we can conclude that gravitational field has its influence only within that range of height.

• Mathematically

The intensity of gravitational field(e) can be expressed as ratio of force (F)felt by an object to the mass(m) of an object when comes under the influence of earth .

                      e = F/m

Note : if we think about the source of gravitational field ,we can conclude that earth & all its mass makes a combined gravitational pull.

🔶How to feel an Electric Field ?

Next, considering electrical field, before studying electrical field, let us answer one question.

What is the source of electrical field?

If we try to answer the above question, then we find that electrical charge can be the source of electrical field, either positive or negative.

Again in order to answer above question, if we generate a charge by rubbing some object like a glass rod or comb over hair after that when we take the rod or comb to a small piece of paper, we find that paper piece gets attracted towards the rod or comb.

If we focus on the above activity then we find that, firstly we have generated some charge on rod or comb by rubbing ,which works as a source of electrical field & secondly when the paper piece comes under the influence of this electrical field it gets attracted.Thirdly we can consider small piece of paper as an atom & the valance electron in the outer shell of the atom gets attracted when comes under the influence of charge on the comb or electrical field.

• Mathematically

The intensity of electrical field (E) can be expressed as ratio of force (F) felt by an charge to the charge (q),which comes under the influence of electrical field .

                            E = F/q

🔶How to feel Magnetic Field ?

Finally considering magnetic field, let us visualize on an activity, where we take two piece of magnet close to each other, then we find that they attracts towards each other.

What we find it here is some magnetic lines of forces acts in between them.

In order to feel the magnetic field, if we take a metal piece or another bar magnet it feels a force of attraction, such force is only because of magnetic field.

Like positive or negative charges in electrical field if we consider mono pole (hypothetical) in magnetic field we find, north-pole shows an outward magnetic lines of forces & south-pole inwards.

• Mathematically

The intensity of magnetic field (H) can be expressed as ratio of force (F) felt by a north-pole or a south pole when comes under the influence of magnetic field.
                       H = F/ Pole strength,m

                                                                Comparison Table

	Gravitational Field	Electrical Field	Magnetic Field
Source	Mass	Charge	Pole Strength (North pole or South Pole)
Fundamental Form	F/mass	F/charge	F/pole strength