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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.  

Categories within Electricity & Magnetism

Charge

Postings: 252

A charge is the physical property of matter that causes it to experience a force when close to other electrically charged matter.

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

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

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 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

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

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

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

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

The Polarization of Light

Please solve and explain Two pieces of Polaroid are held against the light. Can you look through them by themselves? When they are stacked on top of each other? What happens if you rotate one of the Polaroids while keeping the other one fixed. Explain why you observe a variation in transmitted light intensity.

An electron moves in a force field due to a uniform electric field E and a uniform magnetic fiedl B that is at right angles to E. Let E = jE and B = kB. Take the initial position of the electron at the origin with initial velocity vo = ivo in the x direction. Find the resulting motion of the particle. Show that the path of motion is a cycloid. x = a sin wt + bt y = a (1 - cos wt) z = 0

An electron moves in a force field due to a uniform electric field E and a uniform magnetic field B that is at right angles to E. Let E = jE and B = kB. Take the initial position of the electron at the origin with initial velocity vo = ivo in the x direction. Find the resulting motion of the particle. Show that the path of motio

Lightbulbs and Fuses

How many 100-W lightbulbs connected to 120V can be used without blowing a 15-A fuse? I = P/V I = 100W/120V = .8A I divided 15 A by .8 A to equal 18.75; therefore, you could use 18 bulbs. Why is the answer incorrect? You don't need to provide a solution - just a reason why this solution is incorrect.

Cross-Beam Systems

With respect to the cross-beam system shown in the Figure (see attached), if L_B - 4(L_A), what part of the total load P is carried by beam A? By beam B? Assume that both beams have identical section properties and have the same end conditions. Please see the attached file.

Assessment of Static Determinacy

The attached diagrams show a rectangular plate held by joints defined by pins and links. Which ones have: A) Static determinancy B) Overconstraint C) Underconstraint D) Overconstraint in some DoF, Underconstraint in others

Motion of a charged particle in electric and magnetic field. Crossed Fields

Please review my solution to the problem and explain in detail what I may be doing wrong and what concepts I may not be applying correctly. I am not sure if I am apply the crossed fields concept correct in presuming that B is perpendicular. The problem states: An electron has an initial velocity of (12.0j + 15.0k) km/s

Heating Materials

Why is a metal spoon easier to heat up than a ceramic cup and When a compass is placed near an electrical circuit and the circuit is turned on, the needle will jump.

A Balmer's Series Problem

Using Balmer's Series equation: 1/wavelength = R[1/2^2 - 1/n^2] where n = 3,4,5... What number should be in place of the 2 in the denominator for a spectrum to be emitted in the infrared region? ((There was a sample problem for a red line in the hydrogen spectrum: 1/wavelength = (1.097 x 10^7m^-1)[1/4 - 1/9]. This totalled

Determining a B-Field from a Thomson experiment.

When Thomson experimented with his apparatus, he noticed that in one run, the electron beam dropped 1.35 cm. when it emerged from the parallel plate region (where the electric and magnetic fields were present). If L = 5 cm, E = 1000 volts/meter, determine the value of the B-Field in Tesla. Should I use the equation B~Sq. Root

Relativity and Time-Independent Magnetic Field

Assume that, in S, there is a constant magnetic field and no electric field. Show that E' = V cross B' in S'. Note the prime on the right hand side. So E' is perpendicular to V and B'.

Monochromatic Plane Wave

Write the (real) electric and magnetic fields for a monochromatic plane wave of amplitude Eo, frequency w, and phase angle zero that is (a) traveling in the negative x direction and polarized in the z-direction; (b) traveling in the direction from the origin to the point (1,1,1), with polarization parallel to the xz plane. In ea

Force between electrons moving side by side

Calculate the force, a observed in the laboratory, between two electrons moving side by side along parallel paths 1 millimeter apart if each has a kinetic energy of (a) 1 electronvolt and (b) 1 megaelectronvolt

Sources of Magnetic Field

A proton (charge +e) traveling with a velocity of v(with arrow over top)=1x10^4m/si^ (ihat) + 2 x 10^4m/sjhat (jhat) is located at x=3m, y=4m at some time t. Find the magnetic field at (a) x = 2m,y=2m;(b)x=6m,y=4m;and(c)x=3m,y=6m.