Explore BrainMass
Share

# Electricity & Magnetism

### 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 the

### 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<Founda

### 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?

### Center of Mass and Magnetic Materials

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

### Straight wire of 0.10 m in length, carried an electric current

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?

### Physics: Find the Poynting vector

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.

### 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

### Fields 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

### Grounded Metal Plates: Electricity, Magnetism and Waves

Two infinitely long, grounded metal plates , at y=0 and y = a, are connected at x = +/- b by metal strips maintained at constant potential, Vo (insulated at the corners). Find the potential inside the rectangular pipe. Please show: a) A sketch of the set up b) The general form of V(x,y) before any boundary condition have

### 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.

### Physics Problem - Electricity, Magnetism and Waves

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

### Physics - Electricity, Magnetism and Waves

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.

### Magnitude of velocity of a electron

An electron e= 1.6*10^-19C, m= 9.1*10^-31kg is accelerated through a potential difference of 2kV. It then passes into a magnetic field perpendicular to its path, where it moves in a circular arc of diameter 0.36m. 1.) What is the magnitude of the velocity of the electron in a magnetic field? 2.) What is the magnitude of t

### 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

### Physics - Electricity, Magnetism and Waves - Theory

How can electric potential and current be determined? What does it mean to have a 9 volt battery? How can voltage be measured?

### Insulating charged sphere and the electric field in different regions of space.

A.) An insulating sphere with a radius of 3.5×10^-2 has a uniform charge density of 2.52 uC/m^3 throughout its volume. Find the magnitude of the electric field at a point 5.7×10^-2 m from the center of the sphere. Find the magnitude of the electric field at the surface of the sphere. Find the magnitude of the elect

### A positive charge q1 is located to the left of a negative charge -q2. On a line passing through the two charges, there are two places where the total potential is zero. The first place is between the charges and is 4.00 cm to the left of the negative charge. The second place is 7.00 cm to the right of the negative charge. a. What is the distance between the chares, d?b. Find q1/q2, the ratio of the magnitude of the charges.------------ diagram --------------

A positive charge q1 is located to the left of a negative charge -q2. On a line passing through the two charges, there are two places where the total potential is zero. The first place is between the charges and is 4.00 cm to the left of the negative charge. The second place is 7.00 cm to the right of the negative charge. a.

### 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.

### Electric current: Drift Speed and the Current Density

1. A small but measurable current of 1.2X10^-10 A exists in a copper wire whose diameter is 2.5mm. The number of charge carriers per unit volume is 8.49X10^28 m^-3. Assuming the current is uniform, calculate the (a) current density and (b) electron drift speed. 2. Near Earth, the density of protons is the solar wind (a stream

### Determining the Magnitude of an Electric Field

A long, thin straight wire linear charge density lamba runs down the center of a thin, hollow metal cylinder of radius R. The cylinder has a net linear charge density 2lamba. Assume lamba is positive. Please see attached file for additional information.

### 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.

### 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.

### Electromagnetic Wave

** Please see the attached file for the full problem description ** 16. Which of the following expressions is correct for the transmitted intensity of an unpolarized beam of light with an intensity Ii passing through a polarizer 17. A certain part of the electromagnetic spectrum ranges from 200 nm to 400 nm. What is the hi

### 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

### Calculate the Magnetic Field in Thomson's Experimentt.

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.