Field in Physics

Dhristi JEE 2022-24

What is a Field in Physics?

In Physics, a field refers to a physical quantity that is assigned to every point in space or spacetime. A field is seen as spread throughout a large region of space and it influences everything in its vicinity.


An electromagnetic field includes both electric and magnetic fields, where the electric and magnetic fields lie perpendicular to each other. Here, we will learn the field definition in Physics and describe the scientific definition of a field.


Physics deals with interactions between the fundamental constituents of the observable universe and the structure of matters.


Physics conserved all aspects of nature on both macroscopic and submicroscopic levels. Physics is the basic physical science. In recent times physics is used for the discovery and formulation of new fundamental laws. In physics, a field is a region in which each point is affected by a force. The objects fall on the ground because of the earth's gravitational force.


An electric field is surrounded by an electric charge, when another charge is placed in this field it experiences some electric force that can attract or repel it. The strength of field and force experienced in a particular region are represented by field lines. The closest line has a maximum force of attraction or repulsion and when the field line goes away it represents that the force of attraction and repulsion is weak. An electromagnetic field includes both an electric field and also a magnetic field. Where both electric and magnetic fields lie perpendicular to each other.


Field Definition Physics

So, we got a brief idea of what is a field in Physics. Now, we will learn about it in detail, starting with field definition physics. In physics, a field is a physical quantity, which we represent by a number or as a tensor quantity that has a value for each point in space and time (spacetime). 


For example, on a weather map, we describe the surface temperature by assigning a number to each point on the map; the temperature can be considered at a certain point over an interval of time, to study the dynamics of temperature variations.


Field Definition Science

Let’s consider an example to understand field definition in Physics.


We can describe a surface wind map by drawing an arrow to each point on a map that points to the wind speed and direction at that point. This example discusses the vector field or a 1-dimensional tensor field. 


Field theories, mathematical descriptions of how field values vary in space and time are found everywhere in physics. 


For instance, the electric field is a rank-1 tensor field, and we can formulate the full description of electrodynamics in terms of two interacting vector fields at each point in spacetime, and sometimes as a single-rank 2-tensor field theory.


Define Field Force in Physics

In Physics, the field is a region in which each point is affected by a force. We might have seen that objects fall to the ground because they are pulled by the force of the earth’s gravitational field.


For the Field Force Definition In Physics, let’s consider the following examples:


When we place a paperclip in the magnetic field surrounding a magnet, a clip gets attracted and pulls toward the magnet.


Also, two like magnetic poles repel each other when one is placed in the other’s magnetic field and two unlike magnetic poles attract each other. 


An electric field surrounds an electric charge. During our experiment on the electrostatic field, we see that when another charged particle is placed in the region of the electric field, a charge experiences an electric force that either attracts or repels it. 


However, the strength of a field, or the forces in a particular region, can be represented by field lines. So, the closer the lines are, the stronger the forces persist in the area of the field.


Field Force Definition in Physics

Field force definition is very important to understand. The definition says that a force field is a vector field that represents a non-contact force acting on a particle at different positions in space.


We write the field force in the form of vector as \[\overrightarrow{F}, where  \overrightarrow{F(x)}\] is the force acting on a particle, which is at position \[\overrightarrow{(x)}\].


Field Force in Physics Examples

Let’s understand a few field force examples:

We can consider an example of rotatory motion. Here, when a particle ‘P’) is at one point inside the stone and on rotating the stone, all the particles also start making a circular motion. The force applied to the stone is a centripetal force and a field generates around it. Now, when a frictional force of air resistance acts on it, the stone stops eventually. 


Another example is the gravitational force. Let's suppose that small mass ‘m’ is standing in the air inside the room and there is an invisible large mass ‘M’, there is an imaginary field that attracts small mass ‘m’ towards itself. The same happens with the earth, it attracts or pulls all the masses in the air towards its center.


A body is of mass ‘m’ and acceleration due to gravity is ‘g’, so the force of gravity or weight is given by:


\[\overrightarrow{(F)} = mg \]


All the charged particles remain static. On applying an electric field, they start moving from one end to another. In this way, the electric field generates under the influence of electric force. The expression for the electric force on a charged particle q is given by:


\[\overrightarrow{(F)} = \overrightarrow{qE} \]


A field model of Physics can be understood by an example of gravitational force.


A gravitational force field is a model that can be used to explain the influence of gravitational force. It states that a massive body extends into the space around itself, producing a force on another massive body.


For example, a force of attraction between the Sun and planets helps planets revolve around the Sun.


The Scope of Physics

Mechanics

The mechanic is generally taken for the study of the motion of objects under the applied force. Classical mechanics is considered applied mathematics. It consists of two types  1. Kinematics- the description of motion. And second is dynamics -- the study of the action of force.


In classical mechanics, the laws are formulated for point particles and shape and other intrinsic properties are neglected.


The three laws of motion are given by Issac Newton. He is the founder of classical mechanics which also recognized that forces are vectors. The first law is also called laws of inertia which say that unless an external force on an object, the object does not change its position i.g. The object at rest remains to rest and motion remains motion. Newton’s second law equates the net force on an object to the rate of change of its momentum. The third law of motion says that the reaction is equal action. 


The Gravitation

Newton's gravitational laws state that every particle in the world attracts another particle with a force that acts along the line joining them and whose strength is directly proportional to the product of their masses and inversely proportional to the square of their separation.


This force is called gravitational force.No further principles are required to understand the principal aspects.


Examples of Fields

  1. The area at the park where kids play baseball.

  2. The Magnitude of Earth's Gravity- The sun exerts a very high amount of gravitational force on the earth. The total value of the gravitational field is directly proportional to the diameter of the body. The Sun's diameter is 1.3927 million km. The diameter is huge therefore this means that the sun can exert a large amount of field force on the object present around it.

  3. Same Poles of the Magnet- A magnet consists of two north and south poles. And both poles have their magnetic field when the two magnet poles are arranged in constructive interference the magnet gets attached. In case of destructive interference, the magnet gets replied to each other.


   This is a real-life example of a field force.

FAQs on Field in Physics

1. How many types of fields are in Physics and its name?

There are three types of physics: 

  1. Gravitational Field, 

  2. Electric Field, and 

  3. Magnetic Field.

2. Does the field exist?

Yes, Michael Faraday invented the field construct as a physical one.

3. What are fields made up of?

Electromagnetic fields are made up of photons.

4. Do fields have mass?

The field has no mass.

5. Particles have fields?

Carroll's stunner, at least to many non-scientists, is this: Every particle is a field.

6. Can you create a force field?

Force fields are not only possible, they already exist! They're just not human-made.

7. Do quantum fields exist?

Quantum field exists.

8. State Some Examples of Field Physics.

Examples of Field in Physics are:

  • Electrostatic Charge Forces

Let’s suppose that you rub a balloon with a piece of wool and then bring a thread or a feather around it, you can easily trace an electric field around the balloon.


  • Magnetic Field Forces

Take an iron nail and wind a coil around the nail. Now, connect one end of the coil to the power source viz: battery, and pass an electric current through it. You would observe that the magnetic field generates around the nail.


Now, bring a magnetic compass in the vicinity of the nail, you will observe that the needle shows the magnetic force effect via a deflection.

9. Describe the Term ‘Magnetic Force.’

A Sound Produced by Motors, viz: humming, beeping, and clunks come from some kind of coil of wire inside the motor carrying an electric current generates a magnetic field; this magnetic field moves a different chunk of metal or induces a voltage in another coil of wire.


All of the electronics items around you like the most battery-powered ones have coils of wire called inductors that are used to store energy in a magnetic field as part of transforming that energy into a lower or higher voltage for some electronic circuits of lamps, heating elements, microchips, and speakers.


Other applications are:

  • Magnetic forces in a Particle accelerator

  • Floppy drives and hard disks use magnetic forces in them.

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