Electricity and Magnetism Answers

An electron experiences a magnetic force of magnitude 4.60 X 10^-15 N when moving at an angle of 60.0 with respect to a magnetic field of magnitude 3.50 X 10^-3 T. Find the speed of electron

A)you may have noticed that many trucks have to be identical verticaly oriented antenae: One mounted on each side of the driver cab. Suppose that two such dipole antennae separated by a distance of l= 3 m are driven by identical currents I₀e^(-2(pi)jft with f =27 MHz. What is the intensity of radiated power in the plane normal to and through the middle of of the antena as a fuction of an angle ?what is the patern if the antenna are driven exactly Pi radius out of phase ? How do you think antena on the truck are driven and why?

B) Suppose that three identical vertically oriented dipole antenna are aranged in a line .For definteness, let the first be at the origin, the second be at (x,y,z) =(a,0,0) and the third be at at (x,y,z) =(2a,0,0) Assume that the first is driven by the curent I₀e^-jwt the second by I₀=e^-j(wt+pi/2) and the third by I_0e^-j(wt-Pi/2). Asume that the antenne are each small compared to a wavelength a (e.g Lambda/8 , lambda/4, 3lambda/8 , and lambda /2. Note how the radition is focused in one .

The radiation field carries away the rotational energy of a star (as well as its angular momentum) and we can observe this pin down as a change in the period of the pulsar. Suppose the star has a moment of inertia I, (1)show that the angular frequency of rotation changes as a function of time according to dw/dt = -Cw^3 (w=omega=angular velocity). (2)Find C (3)Solve this differential equation with the boundary condition that at t=0, the period is T.(4)If neutron star was spinning much more rapidly in the past (assume so), how old is it?

The period of the crab pulsar is 33 ms and its observed value of T is 1263 years. Assuming the crab neutron star has a radius of 112km, and angle where magnetic dipole moment is inclined to the star rotation axis is 90, and a moment of inertia of 10⁴⁵ gcm², what is the approximate magnitude of the surface B necessary to account for the observed spin down of the crab pulsar? What is the power radiated?

triply ionized particles in a beam carry a net positive charge of 3 elementary charge units, the beam enters a magnetic field of 4.0*10^-2T the particles have a speed of 9.0*10^6m/s

Three charges 2q, 4q and 2q are to be placed on a 1.0 m long straight wire. 

Determine the positions where the charges should to be placed so that the potential 

energy of the system is a minimum.

A uniform electric field is directed along the x-axis between the parallel plated of a charged capacitor, separated by a distance. A positive point charge of mass is released from rest at point A next to the positive plate and accelerates to point B next to the negative plat.

Find the speed of the particle at point B if the motion is under constant acceleration.

Three charges were present inside the coil. The charges were labeled “a”, “b”, and “c”. Charge “a” has a value of 20µc, charge “b” has a value of -50µc and charge “c” has a value of 15µc. Each charge has a distance of 5m to each other. 

a. What is the total force between charges “a” and “b”?

b. What is the total force between charges “b” and “c”?

c. What is the total force and direction of the charges assuming that our charge “a” is the starting point?

suppose that the magnetic field in some region has the form B=kzx. Find the force on a square loop lying in yz plane and centered at origin. if it carries a current I, flowing counterclockwise when you look down the x axis

Consider a hollow charged shell of inner radius a and outer radius b . The volume

charge density is ρ(r) = k

r

2

( k is constant) in the region a < r < b. The magnitude

of the electric field produced at distance r > a is ?