Electrostatics equations

This Section 2.6 discusses how Maxwell's equations strongly constrain the behavior of electromagnetic fields at boundaries between two media having different properties, where these constraint equations are called boundary condition s. Section 2.6.2 discusses the boundary conditions governing field components perpendicular to the boundary ...

Electrostatics equations. The principle of independence of path means that only the endpoints of C in Equation 1.4.1, and no other details of C, matter. This leads to the finding that the electrostatic field is conservative; i.e., (1.4.2) ∮ C E ⋅ d l = 0. This is referred to as Kirchoff's voltage law for electrostatics.

The induced electric field in the coil is constant in magnitude over the cylindrical surface, similar to how Ampere's law problems with cylinders are solved. Since E → is tangent to the coil, ∮ E → · d l → = ∮ E d l = 2 π r E. When combined with Equation 13.12, this gives. E = ε 2 π r.

The electric potential (also called the electric field potential, potential drop, the electrostatic potential) is defined as the amount of work energy needed per unit of electric charge to move this charge from a reference point to the specific point in an electric field. More precisely, it is the energy per unit charge for a test charge that ...electrostatic and vector potentials, are discussed in Section 3.4. The electrostatic potential (a function of position) has a clear physical interpretation. If a particle moves in a static electric field, ... Equation (3.2) is more complex than (3.1); the direction of the force is determined by vector cross products. Resolution of the cross ...Electric field work is the work performed by an electric field on a charged particle in its vicinity. The particle located experiences an interaction with the electric field. The work per unit of charge is defined by moving a negligible test charge between two points, and is expressed as the difference in electric potential at those points. The work can be done, for example, by electrochemical ...2.2 Divergence and Curl of Electrostatic Fields 66 2.2.1 Field Lines, Flux, and Gauss s Law 66 2.2.2 The Divergence of E 71 2.2.3 Applications of Gauss s Law 71 2.2.4 The Curl of E 77 2.3 Electric Potential 78 2.3.1 Introduction to Potential 78 2.3.2 Comments on Potential 80 2.3.3 Poisson s Equation and Laplace s Equation 83Third particle is called electron (e) and they are placed at the orbits of the atom. They are negatively charged "-". Electrons can move but proton and neutron of the atom are stationary. We show charge with "q" or "Q" and smallest unit charge is 1.6021x10-¹⁹ Coulomb (C). One electron and a proton have same amount of charge.In that case curlH = J curl H = J. Now the magnetic field can be derived from the curl of the magnetic vector potential, defined by the two equations. divA = 0. (15.6.2) (15.6.2) div A = 0. (See Chapter 9 for a reminder of this.) Together with H = B/μ H = B / μ ( μ μ = permeability), this gives us. I don't know if this equation has any ...

Figure 2.1.1: Fields with zero or non-zero divergence or curl. The differential form of Maxwell's equations in the time domain are: ∇ × ¯ E = − ∂¯ B ∂t Faraday's Law. ∇ × ¯ H = ¯ J + ∂¯ D ∂t Ampere's Law. ∇ ∙ ¯ D = ρ Gauss's Law. ∇ ⋅ ¯ B = 0quad Gauss's Law. The field variables are defined as: ¯ E electric ...The electrostatic force is thus a sum of a DC force and a time-harmonic force at the excitation frequency. Note that in this derivation, we are ignoring the small DC component proportional to v_0^2 and a force component at twice the excitation frequency. We can similarly derive the expression for the mechanical force for linear time-harmonic analysis with a DC bias.Electromagnetic Field Theory is a course offered by Purdue University's Department of Electrical and Computer Engineering. The course covers topics such as Maxwell's equations, wave propagation, radiation, and scattering. The course webpage provides a pdf file of the lecture notes, which include detailed derivations, examples, and exercises. The pdf file is a useful resource for students and ...The total charge on a hoop is the charge density of the plane, σ , times the area of the hoop, [area of a very thin hoop] d Q h o o p = σ ⋅ ( 2 π r ⋅ d r) The electric field at the location of q created by a hoop with radius r , containing charge Q h o o p is, d E h o o p = 1 4 π ϵ 0 σ 2 π r d r ℓ 2 cos θ. Now we know the field ...Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell's equations. Various common phenomena are related to electricity, including lightning, static ...(a) Verify that this field represents an electrostatic field. (b) Determine the charge density ρ in the volume V consistent with this field. Solution: Concepts: Maxwell's equations, conservative fields; Reasoning: Conservative electrostatic fields are irrotational, ∇×E = 0. Details of the calculation:

Magnetic fields are generated by moving charges or by changing electric fields. This fourth of Maxwell's equations, Equation , encompasses Ampère's law and adds another source of magnetic fields, namely changing electric fields. Maxwell's equations and the Lorentz force law together encompass all the laws of electricity and magnetism.Electronics related equations and more. Electronics Reference (153) Electricity (6) Electrostatics (5) Coulomb's Law Electric Field Gauss's Law Electric Flux Density Electrical Potential Difference Magnetism (4) Electromagnetism (7) Magnetic Circuit (7) Electromagnetic Induction (2) Resistors (2) Capacitors (7) Inductors (8) Transformer (1)Electrostatics. Electrostatics, as the name implies, is the study of stationary electric charges. A rod of plastic rubbed with fur or a rod of glass rubbed with silk will attract small pieces of paper and is said to be electrically charged. The charge on plastic rubbed with fur is defined as negative, and the charge on glass rubbed with silk is ... The fundamental equations of electrostatics are linear equations, ∇·E = ρ/ε0, ∇×E= 0, (SI units). The principle of superpositionholds. Theelectrostatic force on a particle with charge q at position ris F = qE(r). ∇×E = 0 <==> E= -∇Φ, ∇2Φ = -ρ/ε0. Φ is the electrostatic potential. Important formulas:The field of electrostatics covers the fields and forces associated with static electric charge distributions. Wolfram|Alpha provides formulas for computing electric field strength and force. Examine electric field equations for many different charge distributions. Compute the equations, electric fields and forces associated with unmoving charges.

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for any closed box. This means that the integrands themselves must be equal, that is, ∇ → ⋅ E → = ρ ϵ 0. This conclusion is the differential form of Gauss' Law, and is one of Maxwell's Equations. It states that the divergence of the electric field at any point is just a measure of the charge density there.Another of the generic partial differential equations is Laplace’s equation, \(\nabla^{2} u=0\). This equation first appeared in the chapter on complex variables when we discussed harmonic functions. Another example …Chapter 2. Electrostatics 2.1. The Electrostatic Field To calculate the force exerted by some electric charges, q1, q2, q3, ... (the source charges) on another charge Q (the test charge) we can use the principle of superposition. This principle states that the interaction between any two charges is completely unaffected by the presence of other ...Poisson's Equation (Equation 5.15.1 5.15.1) states that the Laplacian of the electric potential field is equal to the volume charge density divided by the permittivity, with a change of sign. Note that Poisson's Equation is a partial differential equation, and therefore can be solved using well-known techniques already established for such ...

Upon replacing in the expression for ΔE Δ E, one finds that: ΔE ≈ϵ1 +ϵ2 +Vcoul Δ E ≈ ϵ 1 + ϵ 2 + V c o u l. where. ϵ = ∫d3k q2 2ε0k2 ϵ = ∫ d 3 k q 2 2 ε 0 k 2. is the self interaction energy of the charges with themselves (can be interpreted as the emission and absorption of a scalar photon by the same charge) and.Third particle is called electron (e) and they are placed at the orbits of the atom. They are negatively charged "-". Electrons can move but proton and neutron of the atom are stationary. We show charge with "q" or "Q" and smallest unit charge is 1.6021x10-¹⁹ Coulomb (C). One electron and a proton have same amount of charge.Electrostatic discharge, or ESD, is a sudden flow of electric current between two objects that have different electronic potentials.Equation, Electrostatics, and Static Green’s Function As mentioned in previously, for time-varying problems, only the rst two of the four Maxwell’s equations su ce. But the equations have four unknowns E, H, D, and B. Hence, two more equations are needed to solve for them. These equations come from the constitutive relations. 5.11: Kirchoff's Voltage Law for Electrostatics - Differential Form The integral form of Kirchoff's Voltage Law for electrostatics states that an integral of the electric field along a closed path is equal to zero. In this section, we derive the differential form of this equation.Electrostatic approximation. Electrostatic potential. As the electric field is irrotational, it is possible to express the electric field as the gradient of a scalar function, , ... Electrostatic energy. Electrostatic pressure.c) where in the region the electric field would be zero. (Hint: 2 equations) 8. A plastic sphere carrying a negative charge of 3.2 x 10-19 C is held stationary by an electric field of 2.0 x 104 N/C. What is the weight of the sphere? 9. As shown to the right, two identical 1.0 x 10-4 kg balls carry identical charges and are suspendedTherefore, in the parallel plate capacitor, the capacitance is: C =. Where, C is the capacitance of the parallel plate capacitor. κ is the dielectric constant. is the permittivity of the free space. A is the area of parallel conducting plates. D is the separation between parallel conducting plates.

3.4: Electrostatics of Linear Dielectrics. First, let us discuss the simplest problem: how is the electrostatic field of a set of stand-alone charges of density ρ(r) modified by a uniform linear dielectric medium, which obeys Eq. (46) with a space-independent dielectric constant κ. In this case, we may combine Eqs.

3. Let me begin by noting that for a surface with charge density σ σ, we know the component of the electric field perpendicular to the surface is discontinuous. This relation is given as. Eabove −Ebelow = σ ϵ0n^, E a b o v e − E b e l o w = σ ϵ 0 n ^, or equivalently in terms of the potential. ∇Vabove − ∇Vbelow = − σ ϵ0n ...Basic principles of electrostatics are introduced in order to explain how objects become charged and to describe the effect of those charges on other objects in the neighboring surroundings. Charging methods, electric field lines and the importance of lightning rods on homes are among the topics discussed in this unit.Electrostatic Potential and Capacitance 47 (ii) Equation (2.2) defines potential energy difference in terms of the physically meaningful quantity . Clearly,work potential energy …The field of electrostatics covers the fields and forces associated with static electric charge distributions. Wolfram|Alpha provides formulas for computing electric field strength and force. Examine electric field equations for many different charge distributions. Compute the equations, electric fields and forces associated with unmoving charges.2 V=0, The Laplace equation electrostatics defined for electric potential V. If g =- V then 2 v=0, the Laplace equation in gravitational field. 2 u=0, u is the velocity of the steady flow. In general, the Laplace equation can be written as 2 f=0, where f is any scalar function with multiple variables. Applications of Laplace Equation2.2 Divergence and Curl of Electrostatic Fields 66 2.2.1 Field Lines, Flux, and Gauss s Law 66 2.2.2 The Divergence of E 71 2.2.3 Applications of Gauss s Law 71 2.2.4 The Curl of E 77 2.3 Electric Potential 78 2.3.1 Introduction to Potential 78 2.3.2 Comments on Potential 80 2.3.3 Poisson s Equation and Laplace s Equation 8316.810 (16.682) 6 What is the FEM? Description-FEM cuts a structure into several elements (pieces of the structure).-Then reconnects elements at "nodes" as if nodes were pins or drops of glue that hold elements together.-This process results in a set of simultaneous algebraic equations.FEM: Method for numerical solution of field problems. Number of degrees-of-freedom (DOF)Feb 20, 2022 · State Coulomb’s law in terms of how the electrostatic force changes with the distance between two objects. Calculate the electrostatic force between two charged point forces, such as electrons or protons. Compare the electrostatic force to the gravitational attraction for a proton and an electron; for a human and the Earth.

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In 1812 Siméon Denis Poisson, who had been a student of Lagrange and a disciple of Laplace, took over the scalar potential from Laplace's and Lagrange's studies of gravitation and applied to it in an electrostatic context. Poisson extended Laplace's equation to include the charge density and solved it for several simple cases.In physics, the electric displacement field (denoted by D) or electric induction is a vector field that appears in Maxwell's equations. It accounts for the electromagnetic effects of polarization and that of an electric field, combining the two in an auxiliary field. It plays a major role in topics such as the capacitance of a material, as well ...electrostatics. In electricity: Deriving electric field from potential. …is a special case of Poisson’s equation div grad V = ρ, which is applicable to electrostatic problems in regions where the volume charge density is ρ. Laplace’s equation states that the divergence of the gradient of the potential is zero in regions of space with no ...Value Of Epsilon Naught. The permittivity of free space ( ε0) is the capability of the classical vacuum to permit the electric field. It as the definite defined value which can be approximated to. ε0 = 8.854187817 × 10-12 F.m-1 ( In SI Unit) Or. ε0 = 8.854187817 × 10-12 C2/N.m2 ( In CGS units)The equations describe how the electric field can create a magnetic field and vice versa. Maxwell First Equation. Maxwell's first equation is based on the Gauss law of electrostatic, which states that "when a closed surface integral of electric flux density is always equal to charge enclosed over that surface"Poisson's equation is an elliptic partial differential equation of broad utility in theoretical physics. For example, the solution to Poisson's equation is the potential field caused by a given electric charge or mass density distribution; with the potential field known, one can then calculate electrostatic or gravitational (force) field.The Electrostatic Equations If we consider the static case (i.e., constant with time) of Maxwell's Equations, we find that the time derivatives of the electric field and magnetic flux density are zero: ∂ B ( r , t ) = t 0 ∂ and ∂ E ( r , t ) t = 0 ∂ Thus, Maxwell's equations for static fields become: Look at what has happened!Equation sheet for electrostatics. The following sheet is a summary of the electrostatic quantities. The relationships in the center of the sheet are of general scope, while those on both sides (in green and red) are valid for point charges. All the quantities are in SI units. ….

day's Law; Electrostatics; Magnetostatics; Electrodynamics; Waveguide. 1 Content of the course The topics that will be covered in this lecture are the following: 2.Introduction -Introduction to Fields -Charge and Current -Conservation Law -Lorentz Force -Maxwell's Equations 3.Electrostatics -Coulomb Force -Electrostatic PotentialIn the equation F elect = k • Q 1 • Q 2 / d 2, the symbol F elect represents the electrostatic force of attraction or repulsion between objects 1 and 2. The symbol k is Coulomb's law constant (9 x 10 9 N • m 2 / C 2 ), Q 1 and Q 2 represent the quantity of charge on object 1 and object 2, and d represents the separation distance between ...Electrostatics. Charge, conductors, charge conservation. Charges are either positive or negative. Zero charge is neutral. Like charges repel, unlike charges attract. Charge is quantized, and the unit of charge is the Coulomb. Conductors are materials in which charges can move freely. Metals are good conductors. Charge is always conserved. Electric field lines originate on positive charges and terminate on negative charges. The electric field is defined as the force per unit charge on a test charge, and the strength of the force is related to the electric constant ε 0 ε 0, also known as the permittivity of free space.From Maxwell's first equation we obtain a special form of Coulomb's law known as Gauss's law for electricity.Figure 2.1.1: Fields with zero or non-zero divergence or curl. The differential form of Maxwell's equations in the time domain are: ∇ × ¯ E = − ∂¯ B ∂t Faraday's Law. ∇ × ¯ H = ¯ J + ∂¯ D ∂t Ampere's Law. ∇ ∙ ¯ D = ρ Gauss's Law. ∇ ⋅ ¯ B = 0quad Gauss's Law. The field variables are defined as: ¯ E electric ...These two equations describe completely different things. V = W/Q V = W / Q says that if you have a test charge Q Q, and you want to move it from place-1 to place-2, and it takes an amount of work W W to do it, then the potential (voltage) at place-2 is higher than that at place-1 by an amount V V. The equation may make it may look like V V ...The electrostatic field is defined mathematically as a vector field that associates to each point in space the Coulomb force per unit of charge exerted on an infinitesimal positive test charge at rest at that point. This electrostatic field, and the force it creates, can be illustrated with lines called “lines of force” (or field lines).Physics equations/Electrostatics. where W is work, F is force, d is distance moved, and θ is the angle between the force and the distance moved. PE is the potential energy , which can be used to define …EXAMPLE 1.4. Calculate the electrostatic force and gravitational force between the proton and the electron in a hydrogen atom. They are separated by a distance of 5.3 × 10-11 m. The magnitude of charges on the electron and proton are 1.6 × 10-19 C. Mass of the electron is me = 9.1 × 10-31 kg and mass of proton is mp = 1.6 × 10-27 kg.30. D. 45. D. 53 60 90. q. 0 . 12 35 22: 32 1 : cos: q: 1 : 32 22: 35 12: 0 : q: 0: 33: 34 1: 43 3 The following assumptions are used in this exam. I. The frame of reference of any problem is inertial unless otherwise Electrostatics equations, Maxwell's equations are solved in homogenous mediums 1 and 2 separately. The solutions obtained by doing so are connected via the boundary conditions. In electromagnetic wave problems involving two mediums, boundary conditions for tangential electric fields and normal electric fields are applied to constrain the solutions., (a) Verify that this field represents an electrostatic field. (b) Determine the charge density ρ in the volume V consistent with this field. Solution: Concepts: Maxwell's equations, conservative fields; Reasoning: Conservative electrostatic fields are irrotational, ∇×E = 0. Details of the calculation: , Application of Maxwell Equation. The application and uses of Maxwell's equations are too much to count in the field of electrodynamics. Essentially it provides a description of the behaviour of electromagnetic radiation in the general medium.; Any device that uses electricity and magnetism for its operational purposes is usually on a fundamental level designed based on Maxwell's equations, The Equations that are used for Electricity. Click on an equation below for more information. The two most important equations in electricity are given below. P = V x I power = voltage x current. V = I x R voltage = current x resistance. P = E ÷ t power = energy ÷ time. Q = I x t charge = current x time. E = V x I x t energy = voltage x ..., Physics: Maxwell's Equations, Light and the Electromagnetic SpectrumIntroductionIn the nineteenth century, knowledge of electromagnetism—all those phenomena related to electrical charges, electric currents, and magnetism—moved rapidly from experimental novelty to practical use. At the start of the century, only gas and oil lamps might be found in homes and businesses, but by the end of the ..., This equation describes the electrostatic field in dielectric materials. For in-plane 2D modeling, the Electrostatics interface assumes a symmetry where the electric potential varies only in the directions and is constant in the direction. This implies that the electric field, , is tangential to the xy -plane. With this symmetry, the same ..., This problem is well discussed for the solution of the Poisson equation, ΔV = − 4πρ, a limit of the modified Helmholtz equation for λ = 0. In a seminal work, Weinert [ 12] proposed an elegant and numerically efficient solution of the Poisson equation for periodic charges and corresponding electrostatic potentials without shape approximation., Electricity and magnetism dominate much of the world around us – from the most fundamental processes in nature to cutting-edge electronic devices. Electric and magnetic fields arise from charged particles. Charged particles also feel forces in electric and magnetic fields. Maxwell’s equations, in addition to describing this behavior, also describe electromagnetic radiation. The three ..., Fig. 2.30. Green’s function method allows the solution of a simpler boundary problem (a) to be used to find the solution of a more complex problem (b), for the same conductor geometry. Let us apply this relation to the volume V V of free space between the conductors, and the boundary S drawn immediately outside of their surfaces., Coulomb's Law can be used to calculate the force between charged particles (e.g., two protons). The electrostatic force is directly proportional to the electrical charges of the two particles and inversely proportional to the square of the distance between the particles. Coulomb's Law is stated as the following equation., E = 1 4 π ϵ 0 Q r 2. The electric field at the location of test charge q due to a small chunk of charge in the line, d Q is, d E = 1 4 π ϵ 0 d Q r 2. The amount of charge d Q can be restated in terms of charge density, d Q = μ d x , d E = 1 4 π ϵ 0 μ d x r 2. The most suitable independent variable for this problem is the angle θ ., LIVE Join Vedantu’s FREE Mastercalss What is Electrostatic Force? Charge is the characteristic property of mass. There are two types of charges, positive charge …, The electric potential (also called the electric field potential, potential drop, the electrostatic potential) is defined as the amount of work energy needed per unit of electric charge to move this charge from a reference point to the specific point in an electric field. More precisely, it is the energy per unit charge for a test charge that ..., Gauss Law states that the net charge in the volume encircled by a closed surface directly relates to the net flux through the closed surface. According to the Gauss law, the total flux linked with a closed surface is 1/ε0 times the charge enclosed by the closed surface. Φ = → E.d → A = qnet/ε0. ∮ →E→ ds = 1 ϵo. q., In the study of mechanics, one of the most interesting and useful discoveries was the law of the conservation of energy. The expressions for the kinetic and potential energies of a mechanical system helped us to discover connections between the states of a system at two different times without having to look into the details of what was occurring in between., The value of coulomb's constant of free space is 9 × 109 Nm2/C2. Substitute the value for the magnitude of charges and distance between the charges to obtain the electrostatic forces between two charges. ⇒ F E = k q 1 q 2 r 2. ⇒ F E = 9 × 10 9 N m 2 / C 2 × 5 μ C × 5 μ C ( 1 m) 2. ⇒ F E = 2.25 × 10 − 1 N., The Cost of Electricity. The more electric appliances you use and the longer they are left on, the higher your electric bill. This familiar fact is based on the relationship between energy and power. ... Figure 9.26 This circle shows a summary of the equations for the relationships between power, current, voltage, and resistance., The study of electrostatics has proven useful in many areas. This module covers just a few of the many applications of electrostatics. The Van de Graaff Generator. Van de Graaff generators (or Van de Graaffs) are not only spectacular devices used to demonstrate high voltage due to static electricity—they are also used for serious research. The first was built by Robert Van de Graaff in 1931 ..., Gauss law says the electric flux through a closed surface = total enclosed charge divided by electrical permittivity of vacuum. Let's explore where this come..., This equation perform electrostatic analyses using Gauss' law.. For info about the math of the equation, see the Elmer models manual, section Electrostatics.. Usage. After adding an Elmer solver as described here, select it in the tree view.; Now either use the toolbar button or the menu Solve → Electromagnetic Equations → Electrostatic equation.; Change the equation's solver settings or ..., Fundamentals of Physics II. PHYS 201 - Lecture 1 - Electrostatics. Chapter 1: Review of Forces and Introduction to Electrostatic Force [00:00:00] Professor Ramamurti Shankar: So, I've got to start by telling you the syllabus for this term — not the detailed one, just the big game plan. The game plan is: we will do electromagnetic theory., Electrostatics F~ = qE~ (electric force on a particle with charge q) The electric field at point P due to a small element of charge dq is dE~ = 1 4π 0 dq r2 rˆ where ~r (= rˆr) is …, Mnemonic for electrostatic equations. I tried to add this to the mnemonics thread but it didn't work. This is how I remembered the electrostatic equations for my test on 3/13. On page 161 of the Kaplan physics book there is a little grid as seen below. If you put Coulomb's law in the top left and multiply across the grid by r or divide down the ..., electrostatic and vector potentials, are discussed in Section 3.4. The electrostatic potential (a function of position) has a clear physical interpretation. If a particle moves in a static electric field, ... Equation (3.2) is more complex than (3.1); the direction of the force is determined by vector cross products. Resolution of the cross ..., Steps to drill the 4 electrostatic equations into memory: ALWAYS reference Coulombs law (F = kQQ/r 2 ) as all the formulas originate from Coulombs law. Draw 4 connected boxes (similar to a punnet square) and place Coulombs law in the L upper corner. Place electric field in L bottom corner (E = kQ/r 2 ), Understanding the how/why behind electrostatics (and all physics in general) makes answering these MCAT problems significantly easier. Lets start with Coulomb's Law: F=kqq/r^2. This is the electric force between two particles. Each of these particles is conducting it's own electric field which can impose electric force on nearby particles., 8 de mar. de 2011 ... In math- ematics, Poisson's equation is a partial differential equation with broad utility in electrostatics, mechanical engineering, and ..., Edge effects for the electric field of a parallel plate capacitor are negligible unless otherwise stated. Page 2. ADVANCED PLACEMENT PHYSICS C EQUATIONS., Electric potential energy is a potential energy (measured in joules) that results from conservative Coulomb forces and is associated with the configuration of a particular set of point charges within a defined system.An object may be said to have electric potential energy by virtue of either its own electric charge or its relative position to other …, Reference space & time, mechanics, thermal physics, waves & optics, electricity & magnetism, modern physics, mathematics, greek alphabet, astronomy, music Style sheet. These are the conventions used in this book. Vector quantities (F, g, v) are written in a bold, serif font — including vector quantities written with Greek symbols (α, τ, ω).Scalar …, Figure \(\PageIndex{3}\): Maxwell's equations in sketch form. The four sketches of Maxwell's equations presented in Figure 2.4.3 may facilitate memorization; they can be interpreted in either differential or integral form because they capture the underlying physics., Hey everyone! So this is a pretty helpful equation map/sheet that links all of the electrostatic equations together. The blue boxed equations you will probably never use, they are just there to give structure and show the relation between the main equations. From them you can derive all of the side equations, which are the ones that you will ..., The dimensions of electric field are newtons/coulomb, N/C . We can express the electric force in terms of electric field, F → = q E →. For a positive q , the electric field vector points in the same direction as the force vector. The equation for electric field is similar to Coulomb's Law.