Electricity and Magnetism Answers

What do you understand by half-wave rectification of half-wave rectification of an alternating current? Obtain the following values of half-wave rectified A.C.

a)     RMS value

b)     Average value 

DESCRIBE the following:

a)     Dynamically induced emf

b)     Mutually induced emf

c)     Self-induced emf and its method

APPLY the concept to find the direction of induced emf and current by

a)     Fleming’s right hand

b)     Lenz’s law 

A beam of protons, each of which has mass m, and charge qe moving with a velocity V enters perpendicularly a uniform magnetic field with the magnitude B= 2uT directed into plane of the page. After the beam exits the magnetic field, leaving the field in a direction perpendicular to its original direction, the beam enters a uniform electric field with the intensity E = 2.10-8 V/m directed downward existing above a distance d=10 m. The beam travels a distance of 6 cm in the magnetic field. After the proton beam exits the magnetic field, what will be passing time till the proton beam stops in the electric field? (Neglect the effect of gravitation).

The small box provided contains a cell of emf

E

and internal resistance

r

. Using this cell, an ammeter

(with negligible resistance), a variable (but known) resistance (

R

) and a plug key connect the circuit as

shown below.

Note

the meter polarity.

(a)

Does it matter in what order the components are connected? Explain.

(b)

In this experiment

I

is the dependent and

R

is the independent variable. Is this correct? Explain.

(c)

(d)

1

1

r

R

I





E

E

Write down the equation for

E

in terms of the current,

I

, the external resistance,

R

, and the

internal resistance of the cell,

r

.

(E2.1)

Show that equation (E2.1) can be rearranged into a form suitable for plotting a straight-line

graph:

An antiproton is a proton antiparticle. The antiparticle of a particle has the same mass as the particle, but with the opposite charge. When an antiproton encounters a proton, annihilation occurs: the particles disappear and gamma radiation is generated. Therefore, when studying antiprotons, it must be possible to keep the antiprotons separate from ordinary material. This is accomplished by putting the accelerated antiprotons in a magnetic field to orbit a very good vacuum. How large must the diameter of such a vacuum chamber be in order to store antiprotons at a speed of 16 km / s in a magnetic field? The magnetic flux density of the magnetic field is 1.9 mT. 

Near the equator, The field lines of the Earth's magnetic field are approximately horizontal to the north and the magnetic flux density is 50 μT. How large and in what direction must the speed of the electron be in order for the force caused by the magnetic field to cancel out the gravity acting on the electron?

What is a linear conductor? Discuss the conditions under which a metal does not 

behave as a linear conductor.

What is the magnitude of the induced E.M.F of a coil of inductance 30mH in which the current changes from 6A to 2A in 2 seconds?

A changing current induces an E.M.F of 10v across a 0.25H inductor. What is the rate at which the current is changing?