# 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.

Last updated on Jul 15, 2013

#### Categories within Electricity & Magnetism:

Circuits

• Postings:
• 1,010

A circuit is a conductive wire connected by various electronic components.

Elements

• Postings:
• 192

Electrical elements are conceptual representing idealized electrical components.

Charge

• Postings:
• 279

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

Electric & Magnetic Fields

• Postings:
• 640

Areas surrounding electrically charged particles.

Resistance in a transistor circuit

Calculate R1 and R2 if I(D)=20I(B). The transistor is silicon and has a beta value of 100. V(E) = 1V. See attached file for diagram.

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 cur

Derive magnetic field intensity due to a solenoid

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

thompson experiment, mangetic and electric field

I wonder how they can use (237) in (239) when (237) is without magnetic field and (239) is with both magnetic and electric field? The text is taken from this site http://farside.ph.utexas.edu/teaching/em/lectures/node33.html

Electron Density

Use the equation 9.1 to derive electron density( unit: electrons/cm^3) of polystyrene (C8H8)n and Lucite (C5O2H8)n. use the equ 9.2 calculate the Z/A ratio.

Electric and Magnetic Fields and Vectors

At one instant, the electric and magnetic fields at one point of an electromagnetic wave are : E = (220i + 300 j - 50 k) V/m and B = Bo(7.9 i - 7.9j + ak) muT 1. What is the value of a? 2. What is the value of Bo? 3. What is the Poynting vector at this time and position? Find t

Derivation of a Wave Equation about E,B & V,A.

1. Derive wave equation (about E, B ) by using Maxwell`s equations. 2. Derive wave equation (about vector potential, scalar potential) by using Maxwell`s equations. There are no conditions(such as no charges or no current) given, which means I have to solve in a general form! ***I am currently using Reitz's book<Foundat

Physics: What does the applet suggest about an electric current?

Referring to the following link: http://educypedia.karadimov.info/library/Dipolentstehung.gif If the blue lines represent  the electric field, what do the red lines represent? What does the applet suggest about an electric current?

A mass spectrometer has an accelerating potential diff of 34 V, a 0.050 T magnetic field.

A mass spectrometer has an accelerating potential diff of 34 V, a 0.050 T magnetic field. A double charged atom has a radius in the field of 53 mm. Find the mass of the atom in proton numbers

find the centre of mass of an irregularly shaped object which has an irregular mass distribution

1. how would you find the centre of mass of an irregularly shaped object which has an irregular mass distribution? Is it possible for the center of mass to be outside the object? Give an example. 2. describe the origins of magnetism at the atomic level and explain how it is possible for this atomic property to be detected on th

A straight wire of 0.10 m in length, carried 5.0 A of electric current. A uniform magnetic field is orientated at right angle to the direction of the wire.

A straight wire of 0.10 m in length, carried 5.0 A of electric current. A uniform magnetic field is orientated at right angle to the direction of the wire. The force on the wire is 0.02 N. what is the strength of the magnetic field?

Energy: Number of turns on the input coil to step down 206 volts to 15 volts

A transformer is designed to step down the 206 volts to 16 volts. If there are 418 turns on the input coil, how many turns should there be on the output coil? You do not have to enter units for this problem and enter the nearest whole number of turns for the output coil.

Physics: Electromagnetic induction is used in the operation of

Electromagnetic induction is used in the operation of generators. transformers. dynamic microphones. regenerative braking. all of the above.

Maxwell Laws to demonstrate fields that change with time in a harmonic way

See attached file. Demonstrate that for fields that change with time in a harmonic way, Maxwell laws are (see formulas attached).

Physics: Find the Poynting vector in vacuum and explain the result.

An infinite wire having current I oriented along z-axis passes through a small hole in a uniformly charged infinite plane at z = 0. The current is perpendicular to the charged plane (with charge density &#963;) . Find the Poynting vector in vacuum and explain the result.

Physics problems: Resistance, capacitance, electric potential, current, voltage, electons

See attached files for problems. Physics practice sheets.

Effects of Electric Field and Magnetic Field on the Path of a Proton

Protons move in a circle of radius 5.20 cm in a 0.555 T magnetic field. What value of electric field could make their paths straight? Please explain and solve problem.

What magnetic field is required to constrain an electron

What magnetic field is required to constrain an electron with a kinetic energy of 418 eV to a circular path of radius 0.831 m? Please explain and solve problem.

Physics: magnetiaztion in terms of X_m and B

Show that in a linear isotropic magnetic medium: M = [(X_m)(B)]/[(mu_0)(1+X_m)]

Physics: What is the speed of a 590 eV electron? Of a 3.50 keV electron?

Part 1 What is the speed of a 590 eV electron? Part II What is the speed of a 3.50 keV electron? -please explain problem and provide a numerical solution

Electric and Magnetic Fields and Angular Frequency

Write down the (real) electric and magnetic fields for a monochromatic plane wave of amplitude E_0 angular frequency w and phase angle zero that is traveling the in the (0,1,1) direction and polarised in the x-hat direction. Note: You are not given bold k or k so even the 'space' part has to be in terms of w. (see attached

The problem deals with the electric and magnetic field behavior at an interface.

See attached file for complete formulation of the problem. The problem deals with the electric and magnetic field behavior at an interface. The first question asks to show that using Maxwell's equations we can obtain the wave equation for the fields. The second question asks as to draw the fields at the interface. The th

Electricity, Magnetism and Waves

Transformer efficiency

A transformer is designed to change 135 V into 10,000 V, and there are 4800 turns in the primary. How many turns are in the secondary, assuming 100 percent efficiency? turns

Generator in rev/sec

A simple generator has a 760-loop square coil 21.0 cm on a side. How fast must it turn in a 0.670 T field to produce a 150 V peak output? rev/s

Magnetostatics

A current I flows down a wire of radius a. If it is distributed in such a way that the volume current density is inversely proportional to the distance from the axis, what is J?

Polarization of light: Conceptual questions.

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.

Ammeter measuring current is determined.

An ammeter has a sensitivity of 22000 /V. What current passing through the galvanometer produces full-scale deflection? µA

Current and Resistance concepts are analyzed.

The power rating on a light bulb indicates how much power it would dissipate when it is hooked up to the standard household voltage of 120 V (this rating does not mean that the light bulb always dissipates the same amount o power). A) How much power is dissipated in a light bulb that is normally rated at 60W, i instead we ho

Circuits / Charges are depicted.

If a proton moved from 0 V potential to 10 V potential, would its potential energy increase or decrease? If an electron moved from 0 V potential to 10 V potential,would its potential energy increase or decrease? Explain.