Any physical entity is said to be constant only when there is no change occurs with time. Let us discuss about situation of constant electric field.
The electric field is constant when partial derivative of field force per unit charge with time is zero. The constant electric field refers to the electric field is not rapidly alternating and freely moving in the given region. The strength of the electric field will be same throughout the region.
The electric field is associated with the distance between the charges. If the distance between the two charges is not varying with the time, then the field generated due to the charges will be constant. Let us provide some more interesting facts regarding constant electric field in this post.
How is electric field constant?
The electric field depends on the force exerted on the charges. Now, let us focus on how electric field will be constant.
The electric field is constant due to steady charges. When the charges are at stationary state, they acquire potential energy. So some force is required to exert on the unit charge to produce electric field. If the applied force per unit charge is constant, the electric field will be constant.
The concept of constant electric field is also associated with the potential difference arise due to electric field. If the electric potential varies uniformly, the slope of the electric potential will be constant which yields constant electric field. In a wire, the electric field is constant because the flow of electrons along the length of the wire is constant.
Is electric field always constant?
The electric field is associated with the charge distribution in a region and drift velocity. Let us explain whether electric field is always constant or not.
The electric field is not always constant it varies accordingly with the charge distribution and drift velocity. The drift velocity changes with the flow of the charges. Generally, electric field is not continuous because the charge distribution is uneven.
The electric potential also contributes for the constant electric field. Sometimes the electric field across the wire becomes constant due to its constant length so that electric field across the wire becomes zero because no force is required for the charge to flow through them.
Is the electric field constant in a circuit?
The electric field is represented by the flow of current in the circuit. Let us check whether electric field is constant in a circuit or not.
In a circuit, if the steady current is flowing across the circuit, the electric field will be constant. Circuit consists of wires to carry the current, so that the wires can carry finite amount of current due its length and area of cross-section. This makes that circuit exert constant electric field.
The electric field across the circuit is not always constant even though steady current is flowing through them. Some physical condition such as temperature and pressure influences the circuit’s electric field.
Why electric field inside a conductor is constant?
Conductor consists of large number of free electrons and is a passage for the current flow. Let us find the reason for constant electric field in the conductor.
The electric field inside the conductor is always zero not constant because the charges can reside only at the surface of the conductor. There is no charge available at the interior to generate electric field. The potential difference between the two points inside the conductor is also zero.
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If the constant electric field present inside the conductor, then the electrons drift away in opposite direction with constant speed. To avoid such repulsive behavior, there is no charge present inside the conductor and no electric field will generate inside the conductor but electric potential is constant inside the conductor.
What is steady state in electric circuit?
The term steady refers to no change in the physical system. Let us learn the meaning of steady state in electric circuit.
An electric circuit is said to be in steady state if there is constant amount of current is flowing at every point of the circuit. In the practical electric circuits, the steady state is achieved for only short period of time.
At the steady state of electric circuit, the number of charges flowing into the circuit is equal to the number of charges flowing out of the circuit. This means that eventually, the steady state of electric circuit follows the Kirchhoff’s current rule.
Solved Problem
A small charge of 6mC tends to generate constant electric field when a force of 15×10-5N is exerted on it. Calculate the value of constant electric field generated by the charge.
Solution:
Given –charge q=6mC= 6×10-3C
Force exerted on the charge F=15×10-5N
The electric field is calculated using the formula F=qE
Where, E is the electric field.
On rearranging the equation
Substituting the values, we get
E=0.025N/C
Conclusion
Let us conclude this post by stating that the electric field is a vector quantity associated with the electric property of the charges. The constant nature of electric field depends on the potential difference and time derivative of the force per unit charge.
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I am Keerthi K Murthy, I have completed post graduation in Physics, with the specialization in the field of solid state physics. I have always consider physics as a fundamental subject which is connected to our daily life. Being a science student I enjoy exploring new things in physics. As a writer my goal is to reach the readers with the simplified manner through my articles.