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# Electricity & Magnetism

Electricity and Magnetism is a field in physics which looks at the effects on electricity and magnetics on the environment. This field is a major area of work with specialties being circuits, fields, charges, and waves and how they interact with electricity and magnetics.

Electricity is the set of physical phenomena associated with the presence and flow of electric charges. Electricity permits the creation and reception of electromagnetic radiation such as radio waves. Electricity produces electromagnetic fields which act on other charges. It can also occur in several different forms such as an electric charge, an electric current, electric field, electric potential and electromagnets.

Magnetism is a class of physical phenomena that includes forces exerted by magnets on other magnets. Magnetism originates in electric currents and the fundamental magnetic moments of elementary particles. Every material is influenced to some extend by a magnetic field. The magnetic state of a material depends on temperature so that a material may exhibit more than one form of magnetism.

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## BrainMass Solutions Available for Instant Download

### Current Electricity and Equivalent Resistance

1. What is electric current? 2. Describe the phenomena of flow of electric current. Explain the concept of drift velocity. 3. Define electric resistivity and resistance. How does the temperature affect resistivity and resistance? 4. State Ohm's law. 5. Discuss series and parallel arrangement of resistances. 6. Define equiv

### Potential of two concentric spheres

Two concentric spheres have radii a, b (b>a) and each is divided into two hemispheres by the same horizontal plane. The upper hemisphere of the inner sphere and the lower hemisphere of the outer sphere are maintained at potential V. The other hemispheres are at zero potential. Determine the potential in the region a<=r<=b as a

### Electrostatic and Circuits Problems

Please answer the following in the attached document. 7. Electrons leave the cathode of a TV tube at essentially zero speed and are accelerated toward the front by 10,000 V potential. At what speed do they strike the screen? Express this value as a fraction of the speed of light. 8. A charge of -4.00μ C is fixed in place

### The Laplace Equation in Cylindrical Coordinates

Please see the attached file for a question taken from the "Classical Electrodynamic 3rd by Jackson".

### Green's Function and Spherical Harmonics

Please see the attached file. It is taken from "Classical Electrodynamic 3rd by Jackson".

### The Potential of a Disk With a Certain Charge Distribution

Please see the attach file for the question taken from "Classical Electrodynamics 3rd by Jackson".

### Electric Field Around a Conducting Cylinder

Please see the attached file: 3. Consider the case of an infinite conducting cylinder of radius 'a' with a uniform charge per unit length lambda placed in a uniform electric field with the axis of the cylinder perpendicular to the direction of the field. The potential generated by such a system maybe written as: (See attachme

### Chemical Effects of an Electric Current

Describe in details the chemical changes (chemical effects) that take place when electric current is passed through a liquid.

### Potential of a split cylinder

(a) Two halves of a long hollow conducting cylinder of inner radius b are separated by small lengthwise gaps on each side, and are kept at different potentials V1 and V2. Show that the potential inside is given by the following equation (see attached file for equation). (b) Calculate the surface-charge density on each half of

### Parallel Plate Capacitor with a Spherical Boss

See the attached file. A large parallel plate capacitor is made up of two plane conducting sheets with seperation D, oneo f which has a small hemispherical boss of radius a on its inner surface (D >> a). The conductor with the boss is kept at zero potential, and the other conductor is at a potential such that far from the bos

### The method of images

Using the method of images, discuss the problem of a point charge q inside a hollow, grounded, conducting sphere of inner radius a. Find: (a) the potential inside the sphere (b) the induced surface-charge density (c) the magnitude and direction of the force acting on q (d) Is there any change in the solution if the sphere

### Green's function and Electrostatic potential

How do you show that the Green's function is always symmetric under Dirichlet boundary condition but symmetric under Neumann boundary condition only with certain modification? The specific problem is attached below.

### Green's reciprocation theorem

Please see the attach file, The Green reciprocation theorem also attached. it take from " Classical Electrodynamic 3rd by Jackson" Two infinite grounded parallel conducting planes are separated by a distance d. A point charge q is placed between the planes. Use the reciprocation theorem of Green to prove that the total induc

### Deriving the PDE for a vector field from its curl and divergence

See Attached http://farside.ph.utexas.edu/teaching/em/lectures/node37.html How do they come up with the equations in (308) mathematically? Why do (308) give solutions to (285) and (286). Or why do (308) determine whether (285) and (286) have 1 or more solutions? I don't wonder about the proof for why the La place (30

### Problems on Radiation Physics

See the attached file. 1. The peak power of a 6ft. diameter antenna is 10 watts and its duty cycle is 0.250. The wave length is 0.03m/cycle. Find the power density in mw/cm2 at 50 meters from the antenna. 2. The activity of an isotope was determined to be 4000mci on Monday at 10.00 am on Tuesday at the same time its activi

### Current Density in a Spherical Volume

We have a spherical volume with R=1m. Inside a uniform charge density increases with a constant rate of 2 C/(m^3s). The increase is related to a uniform charge density that enters radially through the surface. Use the continuity equation to calculate the current density through the surface. See attached

### Potential Between Grounded Plates

The following is a problem I have been having a difficult time with. Please see attached file for a diagram to help with the problems. A charge q is placed between two grounded infinite parallel conducting planes which are a distance "d" apart (see figure attached). Let ε_r = 1. a) For |a_1| ≠ |a_2| find the electric p

### Solving pointing vectors

Light is directed on the surface of the non-conductive material at an angle of incidence of pi/6, just outside of this surface the intensity is 50(W/M^2). The EM wave is polarized in the plane of incidence. 1. Find the E0 and B0 outside the material. 2. Find the pointing vector outside the material. 3. What is the intens

### Radiation Pressure to Lift

1. You have a laser with an output of 10,000 watts in a .02m diameter beam. Find the radiation pressure. 2. If you have a reflective surface of mass .002kh on the earth, can you lift this with the laser?

### Resistance Based Physics Problems

1. You've made the finals of the Science Olympics! As one of your tasks, you're given 2.0g of copper and asked to make a cylindrical wire, using all the metal, with a resistance of 2.0omega . a) What length (l) will you choose for your wire? Express your answer in meters to two significant figures. b) What diameter (d) wi

### self-inductance-cylindrical-coaxial-cables

A. A long straight cable with radius R carries a current uniformly distributed through its circular cross section. Find the self-inductance per unit length of the cable. Hint: find B inside and outside, then find energy everywhere and relate to the self-inductance (per unit length) B. This cable is now modified to have an ins

### B, H and M due to cylindrical conductor

An infinitely long solid cylindrical conductor of radius R carries a free current density J(s) = Cs^3z distributed over its cross section. The z axis is the long axis of the cylinder. The conductor has a permeability 'mu' which does not equal 'mu-0'. Outside the conductor is a vacuum. A. Find H, B, M inside the conductor and

### Magnetic Field from Magnetic Vector Potential

A sphere is centered at the origin with radius 3m. It has a total charge of 100 micro-Coulombs spread uniformly over its surface and is spinning with 3600 revolutions per minute. 1. What is the magnitude and direction of the magnetic field inside the sphere? a. B=0 2. Given the magnetic vector potential (see in attachment),

### Physcis 2

• Air in a cylinder is compressed to one-tenth of its original volume without change in temperature. What happens to its pressure? Imagine now that a valve is opened in order to restore the initial pressure value. What percentage of the molecules have escaped? • Consider a 40,000 km steel pipe in the shape of a ring that

### Estimating Value of Current Density

I have to estimate the value of current density in terms of total current through the conductor. A wire of a diameter a and has a current I 1. If I is distributed so that J is proportional to the distance from the axis, find J in terms of I. 2. If I is distributed so that J is inversely proportional to the distance from t

### Electric force between two uniformly charged solid hemispheres

A uniformly charged solid sphere with radius R with charged +Q is sliced into two half's along the X-Y plane. Find the force required to keep the two half's together.

### Non-Uniform Surface Charge Density

Please see the attached file. A spherical shell of radius R centered at the origin has a surface charge density (file attached). 1. Setup the Coulomb integral for the electric potential V(z) for any point on the z axis. Find the function. 2. Evaluate V(z) at the origin (z=0) Note: you may need to look up the integral.

### Interaction Energy of Dipoles

More explanation about find the interaction energy: We have the distance given but not the direction. Need to find a general solution in terms of the angles formed by both dipoles. 2 dipole moments (4,5,6)10-4Cm and (-1,2,3)10-4Cm that are 2 m apart. II 1. Calculate interaction energy of the two dipoles. IT 2. -• Calculat

### Photodiode IV Characteristics

Two p+-n abrupt junction diodes are made from silicon and are identical except that the donor levels in the 2 diodes are ND_1=10^15 and ND_2 = 1x10^17 cm-3. Sketch on one set of axes the I-V characteristics of the diodes for operation at room temperature. Label each curve. Also sketch on the same (or similar) axes the I-V curv

### solenoid magnetic field details

Magnetic ﬁeld is a vector quantity {vector B}, therefore, it has two components to represent it: Magnitude {B}, and direction. To ﬁnd the direction, Right Hand Thumb Rule is used, while for magnitude, a basic law of Biot-Savart Law is used. Right Hand Thumb Rule [RHTR} states {in my words} that - if you are given a curre