Explore BrainMass

Electric & Magnetic Fields

An electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the surrounding force of an electrically charged particle exerted on other electrically charged objects. The concept of an electric field was first introduced by Michael Faraday.

The electric field is a vector field with SI units of newton’s per coulombs. The strength of the field at a given point is defined as the force that would be exerted on a positive test charge of one coulomb placed at that point. The direction of the field is given by the direction of that force.

An electric field that changes with time influences the local magnetic field. The electric and magnetic fields are not completely separate phenomena’s. What one observer perceives as an electric field, another observer in a different frame of reference perceived as a mixture of electric and magnetic fields.

A magnetic field is a mathematical description of the magnetic influences of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude. The magnetic field is most commonly defined in terms of the Lorentz force it exerts on moving electric charges.

Magnetic fields are produced by moving electric charges and intrinsic magnetic moments of elementary particles with a fundamental quantum property, their spin. In special relativity, electric and magnetic fields are two interrelated aspects of a single object. This is called the electromagnetic tensor.

Magnetic fields are most often encountered as an invisible force created by permanent magnets. These magnets pull on iron objects that attract or repel other magnets. Magnetic fields are widely used throughout modern technology. 

Categories within Electric & Magnetic Fields

Gauss' Law

Postings: 103

Gauss' Law is the law relating the distribution of electric charge to the resulting electric field.

Ampere's Law

Postings: 43

Ampere's Law is the law that for any states closed loop circuit, the sum of the length elements times the magnetic field in the direction of the length element is equal to the permeability times the electric current enclosed in the loop.

Biot-Savart Law

Postings: 14

Biot-Savart Law is the equation which describes the magnetic field generated by an electric current.

Faraday's Law

Postings: 12

Faraday's Law states that any change in the magnetic environment of a coil of wire will cause a voltage to be induced in the coil.

EM Waves

Postings: 73

Electromagnetic waves are waves of energy consisting of electric and magnetic fields, oscillating at right angles to each other.

Levitation in the electric field near the surface of the earth.

The electric field is defined as the electrostatic force divided by the charge experiencing this force. The Earth's electric field is directed radially inward and is about 150 N/C at the Earth's surface. This arises because in a region of the atmosphere known as the ionosphere, parts of the spectrum of the radiation from the sun

Magnatic Field at a Disk Center

A small/thin circular conducting disk that can carry total current, as represented by 'I'. The current path is circular at every distance from the center of the disk, and the each circle center is the disk center. Find the magnetic field at the disk center, assuming the current density is: 1. Constant 2. Inversely proporti

Interference of Electromagnetic Plane Waves

** Please see the attached file for the complete problem description ** Two plane waves that are spatially and temporally coherent propagate in the x-z plane and intersect at an angle such that each wave makes an angle (please see the attached file) with the z-axis. The figure below shows the k-vectors associated with the two

Near field (electric or magnetic) or far field

Discuss the nature of the wave impedance at a distance of 1 metre from the following devices: (i) A microwave oven operating at a frequency of 2.45 GHz. (ii) A radio-frequency heat-sealer operating at 27 MHz. (iii) The field coil of a 'deactivation pad' operating at 60 kHz. The pad is used in retail stores to demagnetise

Physics: Position and magnitude of electric charge

A +3.0 charge is at and a -1.0 charge is at . At what point or points on the x-axis is the electric potential zero? X = ___________ cm A -2.0 charge and a +2.0 charge are located on the x-axis at and , respectively. At what position or positions on the x-axis is the electric field zero? At what position or pos

Angle of total electric field due to three charges

Show all workings. A charge of +10.7 micro-Coulombs is placed at the origin of a coordinate system. Another charge of -12.6 micro-Coulombs is placed at x = +0.19 m, y = +0.1 m. A third charge of +13.2 micro-Coulombs is placed at x = -0.19 m, y = 0 m. At what angle is the total electric filed is directed at the the point x = 0

Electric field between two charged parallel plates

Please help with the following problem. A uniform electric field exists in the region between two oppositely charged parallel plates 1.53 cm apart. A proton is released from rest at the surface of the positively charged plate and strikes the surface of the opposite plate in a time interval 1.47 * 10^-6 s apart. Part A: Fi

Force on a proton, x and y components, magnitude, acceleration

** Please see the attached file for clarity ** Please provide answer and complete explanation and steps. The electric field at a point in space is 900 900 . Part A What is the x-component of the electric force on a proton at this point? Express your answer numerically, in newtons, to three significant figures.

Electric Fields (Line, Loop and Disc)

Would you please help me to understand the following questions? (1) Consider a line of charge, density ?, length L, lying along the x-axis from 0 to L. Find the electric field E a distance z along the z-axis. What is the limiting value when z >> L ? (2) Find the electric field, E a distance z above a circular loop of charg

A Hybrid || plate capacitor is examined & problems solved

A parallel plate capacitor consists of two plates of surface area (A) spearated by a distance (d.) This capacitor is in turn connected in series to a DC supply of voltage V volts. A slab of material with permitivity k and thickness d/2 is placed between the plates as shown (SEE PROBLEM ATTACHMENT). We can divide the dielctric be

State Energy: Consider an electron with spin magnetic moment u_s

Consider an electron with spin magnetic moment u_s in a strong magnetic field B_z in the z direction. The potential for an electron with spin magnetic moment u_s in a magnetic field B is V=-u_s . B where u_s = -((g_s)(u_B))/(hbar) . S Thus the Hamiltonian is H_0 = ((g_S)(u_B))/(hbar) . B . S = ((g_s)/2)(u_B) . B . sigma

Problems with Electric Fields

A plastic ring of Radius R= 50.0 cm has two small charged beads on it. Bead 1 of charge +2.00 micro Coulombs is fixed in place on the left side of the ring. Bead 2 of charge +6.00 micro coulombs can be moved along the ring. The two beads produce a net electric field of magnitude E at the center of the ring. At what positive and

Determining Electric Field Acting on Protons

Protons are projected with an initial speed v = 9550m/sec into region where the electric potential is given by V = 720z volts. The protons hit a target that lies a horizontal distance of 1.27 mm from the point where the protons are launched. Determine the electric field acting on the protons, and then find the two projection ang

Magnetic force on rod on parallel conducting tracks

See attached file for diagram. Provide step by step calculations for the problem. Parallel conducting tracks, separated by 2.17 cm, run north and south (the figure below ). There is a uniform magnetic field of 1.25 T pointing upward (out of the page). A 0.0404-kg cylindrical metal rod is placed across the tracks and a batter

Electrostatics - Electric field at the centre of two squares

A square with sides of 2m has a line charge density of 3 uC/m throughout its four sides. It is inside a square with a line charge density of -2 uC/m, such that the two squares share the same center. This outer square has sides of 4m. What is the electric field at the center of the set up? Please give a step by step solution,

Physics: Which statements are true about Magnetic forces

Which of the following statements are true about magnetic forces acting on charged or uncharged particles? Choose True or false for the following statements. True False the magnetic force always acts parallel to the direction of motion of the moving charged particle. True False the maximum magnetic force that a charged

Fifteen Questions: Electric Field and Potential.

Problem 1 A charge is moved from one place to another in an electric field. In which of the following situations will the change in potential energy be NON-ZERO? the charge is only moved perpendicular to all electric field lines that it crosses the charge remains unmoved the charge is moved along an equipotential surfa

Potential between concentric conducting spheres

A conducting sphere of radius r1 is suspended by a perfectly insulating thread inside and concentric with a larger conducting sphere of radius r2 and the space between the spheres is a vacuum. A charge q is deposited on the outer sphere. What is the potential difference (as would be measured by a voltmeter) between the two spher

Uniform Magnetic Field

You want to create a uniform (constant and parallel) magnetic field in a small volume of space. The field should be 500 Gauss. You can get a current of 0.8 Amperes from a power source, and you must choose one of the following methods (only one method is correct): a. A single long straight wire, at distance r from t

Finding the Electric Field of a Uniformly Charged Ring

A uniformly charged ring of radius R has a total charge Q. 1) What is the magnitude and direction of the electric field along the axis of the ring? 2) What is electric field potential along the axis of the ring? 3) What is the electric field at the center of the ring? 4) What is the electric potential at the center o

Electrostatic: Spherical charge distribution

Please see the attachment for description. 1.) What is the total charge inside a shpere of radius 1 and center in the origin. 2.) What is the electric field magnitude for points r>R 3.) What is the electric field magnitude for points r<R 4.) At what distance r0 the magnitude of the electric field is the largest. 5

Set of four problems on elecrostatics.

1) A charge +2q is placed at the origin and a second charge -q is placed at x = 3.0 cm. Where can a third charge +Q be placed so that it experiences a zero force? 2) A charge of -4.00 micro C is fixed in place. From horizontal distance of 55.0 cm, a particle of mass 2.50*10^-3kg and charge -3.00 micro C is fired

A wall has a negative charge distribution producing a uniform horizontal electric field. A small plastic ball of mass 0.01 kg, carrying a charge of -80.0 µC, is suspended by an uncharged, nonconducting thread 0.30 m long. The thread is attached to the wall and the ball hangs in equilibrium (as show in the attachment)in the elastic and gravitational fields. The electric force on the ball has a magnitude of 0.032 N. Answer the following four questions.

A wall has a negative charge distribution producing a uniform horizontal electric field. A small plastic ball of mass 0.01 kg, carrying a charge of -80.0 µC, is suspended by an uncharged, nonconducting thread 0.30 m long. The thread is attached to the wall and the ball hangs in equilibrium (as show in the attachment)in the ela

Electrostatics - Nonconducting Spheres

1. A nonconducting sphere has radius R=2.31cm and uniformly distributed charge q = +3.50fC. Take the electric potential at the sphere's center to be Vo = 0. What is V at radial distance (a) r =1.45cm and (b) r = R. ( answer is given as (a) is -0.268mV (b) -0.681mV, please show me the detail, thank you) 2. Two particles,

Two problems on electrostatics

1. Two charged concentric spherical shells have radii 10.0cm and 15.0cm. The charge on the inner shell is 4.00X10^-8C, and that on the outer shell is 2.00X10^-8C. Find the electric field (a) at r = 12.0cm and (b) at r = 20.0cm. 2, Two Large metal plates of area 1.0 m^2 face each other. They are 5.0 cm apart and have equal but

Gaussian Surface around the Room Air Volume Charge

When a shower is turned on in a closed bathroom, the splashing of the water on the bare tub can fill the room's air with negatively charged ions and produce an electric field in the air as great as 1000N/C.Consider a bathroom with dimensions 2.5m X 3.0m X2.0m. Along the ceiling, floor, and four walls, approximate the electric fi

Electric Fields

A 43.2 nC Charge is located at position (x,y) = (1.0 cm, 2.0 cm). At what position (x,y) position is the electric field 1) At -225,000i N/C? 2) At (161,000i + 80,500j) N/C X=? Y=? 3) At (21,000i - 28,800j) N/C X=? Y=?