assignment on magnetism

1. G.H.RAISONI UNIVERSITY
B.TECH MINING
BASIC OF ELECTICAL AND ELECTRONICS
TOPIC:- Sources of electricity-Magnetism
Name:-Mahesh S. Gudadhe Roll No:-13
Guided By:-Professor Deshmukh

2. Definition:-
Magnetism is a force of attraction
or repulsion that acts at a distance.
It is due to a magnetic field, which is
caused by moving electrically charged
particles.
It is also inherent in magnetic
objects such as a magnet.
Magnetism
https://en.wikipedia.org/wiki/Magnetism

3. History of Magnetism
Magnetism was first discovered in the ancient
world, when people noticed that lodestone,
naturally magnetized pieces of the
mineral Magnetite, could attract iron.
The word magnet comes from the Greek term
for lodestone, "magnítis líthos" ,which means a
stone from the region of Magnesia.
https://en.wikipedia.org/wiki/Magnetism

4. Types of Magnetism
https://en.wikipedia.org/wiki/Magnetism#/media/File:Magnetism.svg

5. Magnet Coil Experiment
An electromagnetic coil is an electrical conductor such as
a wire in the shape of a coil, spiral or helix.
Electromagnetic coils are used in electrical engineering, in
applications where electric currents interact with magnetic
fields, in devices as inductors, electromagnets, transformers,
and sensor coils.
 Either an electric current is passed through the wire of the
coil to generate a magnetic field, or conversely an
external time-varying magnetic field through the interior of the
coil generates an EMF (voltage) in the conductor.
https://en.wikipedia.org/wiki/Electromagnetic_coil#/media/File:VFPt_Solenoid_correct2.svg

6. A current through any conductor creates a circular magnetic field around the conductor
due to Ampere's law.The advantage of using the coil shape is that it increases the strength
of magnetic field produced by a given current.Ampere law is given by the formulae:-
Procedure:-
a.Wind a coil of 10 to 20 turns with long leads (say 50 cm).The
coils should be such that a permanent bar magnet can pass
freely through.
b. Connect the long leads to the galvanometer.
c. Move the magnet in the space in and around the coil,
keeping an eye on the galvanometer. Summarize your
observations.
http://practicalphysics.org/magnet-and-coil.html

7. Magnetism Advantages and Disadvantages
Advantages
Magnets are used electrical generators for generating electricity and it is also used in electric
motors for converting electrical energy into mechanical energy.
It is also used in speakers, eclectic bells, maglev trains,TV and computers screens,
telephones, refrigerators etc.
For lifting practice for and transporting large masses of iron in the form of griders.
It is used in electric meters such as galvanometers, voltmeters, ammeters, speedometers
etc.
It is also used in microphones and loudspeakers.
It also plays an important role in modern medical science, such as MRI (Magnetic Resonance
Imaging).

8. Magnets can only work with a limited number of metals.
Many toys contains small magnets and if it is swallowed by child then it will be very
dangerous.
Some times it becomes difficult to control the power of magnetic force.
Electromagnets heat up very fast.
 Electromagnets takes a lot of energy to use.
Disadvantages

9. Fleming's right-hand rule
Fleming's right-hand rule (for generators) shows the direction of induced current when
a conductor moves in a magnetic field.
It can be used to determine the direction of current in a generator's windings.
When a conductor such as a wire attached to a circuit moves through a magnetic field,
an electric current is induced in the wire due to Faraday's law of induction.
The current in the wire can have two possible directions.
 Fleming's right-hand rule gives which direction the current flows

10. The right hand is held with the thumb, first finger and second
finger mutually perpendicular to each other (at right angles),
as shown in the diagram:-
The thumb is pointed in the direction of motion of the
conductor.
The first finger is pointed in the direction of the
magnetic field. (north to south)
Then the second finger represents the direction of the
induced or generated current (the direction of the induced
current will be the direction of conventional current; from
positive to negative)
https://en.wikipedia.org/wiki/Fleming's_right-hand_rule

11. Faraday’ s Law
First law of Faraday’s Electromagnetic Induction state
that whenever a conductor are placed in a varying
magnetic field emf are induced which is called induced
emf, if the conductor circuit are closed current are also
induced which is called induced current.
Second Law of Faraday’s Electromagnetic Induction state
that the induced emf is equal to the rate of change of flux
linkages (flux linkages is the product of turns, n of the coil
and the flux associated with it
https://www.google.co.in/search?q=faradays+all+law+with+pics&rlz=1C1ASUC_enIN697IN697&espv=2&source=lnms&tb
m=isch&sa=X&ved=0ahUKEwiZg6D-
htHSAhWGt48KHZoeCwsQ_AUIBigB&biw=1600&bih=794#imgrc=67mW9xM4VkY5MM:

12. Stimulation on Magnetism
This is the stimulation of
magnetism so we can see
when we move the magnet
around the coil light glow and
according to the direction of
the magnetic field the voltage
is measured in positive or
negative. But in the centre of
the coil the voltage is highly
generated as around the coil.
https://phet.colorado.edu/sims/html/faradays-law/latest/faradays-law_en.html

13. As now we can see that after
changing the poles of the
magnet (from north and south
to south and north) by clicking
the button given below the
voltage is highly positive
https://phet.colorado.edu/sims/html/faradays-law/latest/faradays-law_en.html

14. As again we change the poles
of the magnet(from south
and north to north and south)
and thus the voltage is highly
negative in this case.
https://phet.colorado.edu/sims/html/faradays-law/latest/faradays-law_en.html

15. Problem 1. (a) Find the direction of the force on a proton (a positively charged particle) moving through the
magnetic fields as shown in the figure. (b) Repeat part (a), assuming the moving particle is an electron.
Solution: (a) For a positively charged particle, the direction of the force is that predicted by the right hand rule.
These are: (a’) in plane of page and to left (b’) into the page (c’) outofthe page (d’) in plane of page and toward the
top (e’) into the page (f’) out of the page
(b) For a negatively charged particle, the direction of the force is exactly opposite what the right hand rule
predicts for positive charges.Thus, the answers for part (b) are reversed from those given in part(a).
Numerical

16. Problem 2. A conductor suspended by two flexible wires as shown in the figure has a
mass per unit length of 0.040 0 kg/m.What current must exist in the conductor for
the tension in the supporting wires to be zero when the magnetic field is 3.60T into
the page?What is the required direction for the current?
Answer:- I=0.109A
Problem 3. A thin, horizontal copper rod is 1.00 m long and has a mass of 50.0 g.What is the minimum current in
the rod that can cause it to float in a horizontal magnetic field of 2.00T?
Answer:- I=0.245A
Problem 4. A wire carries a current of 10.0 A in a direction that makes an angle of 30.0° with the direction of a
magnetic field of strength 0.300T. Find the magnetic force on a 5.00- m length of the wire.
Answer:- F= 7.50N
Problem 5. A wire with a weight per unit length of 0.080 N/m is suspended directly above a second wire.The top
wire carries a current of 30.0A, and the bottom wire carries a current of 60.0A. Find the distance of separation
between the wires so that the top wire will be held in place by magnetic repulsion.
Answer:- d = 4.5mm
http://www.just.edu.jo/~aobeidat/PDF/First%20semster%202008/Problems%20and%20solutions%20on%20Magnetism.pdf