lab 8 teknologi elektrik

TITLE : Magnetism

OBJECTIVES

Magnetic Field Strength

i. Understand the magnetic field strength around a coil

ii. Study the factors for producing a magnetic field.

Fleming’s Rule

i. Become familiar with Fleming’s eft & right hand rule

EQUIPMENT LIST

KL - 21001 KL - 13003

KL - 13005 Jumper Wire

Short circuit clips

THEORY

Magnetic Field Strength

In 1819, Hans Christian Oersted discovered that a current produced a magnetic

field when he notice how a wire carrying a current affected a compass. If a number of

wire loops are wound in the same direction to form a coil, more fields will dd to make

the flux lines through the coil even denser. The magnetic field through the coil

becomes even stronger. The more loops there are, the stronger the magnetic field

becomes.

A helically wound coil that is made to produce a very strong magnetic field is

called a solenoid. The flux lines in a solenoid act the sameas in a magnet.they leave

the N poe and go around to the S pole.

The magneting force that is caused by current flowing in a wire is called the

magnetomotive force, mmf. The mmf depends on the current flowing in the coil and

the number of turns in the coil.

Fleming’s Rule

At mentioned before, a magnetic field will be developed around a wire if a

current flows through the wire. If this wire is within a magnetic fields. Fleming’s rules

are usually used to describe the relationships of the magnetic field, current and the

dirction of movement.

Fleming’s rules include left-hand rule and right-hand rule. The left-hand rule,

commonly used to demonstrate the operation of motors, is also called motor’ rule.

The relationship of the existed magnetic field, current in the conductor, and the

moving direction of conductor are shown in Figure 8.2. if the index finger pointing in

the direction of te exsited magnetic field (lines of force), and the middle

fingerpointing in the current flowing in the conductor, then your thumb will point in

the direction that the conductor moves.

Flaming’s right-hand rule, usually used to describe the operation of power

generator’s rule. It is illustrated in figure 8.3. if your thumb pointing in the moving

direction of the magnetic field, then the middle finger will point the direction of

induced current.

EXPRIMENT 8-1 MAGNETIC FIELD STRENGTH

PROCEDURE & RESULT

1. The module KL-13003 on the main unit KL-21001, and locate the block c.

2. The experiment circuit with short-circuit clips. The ammeter (0-1A) is

available from the main unit.

3. Apply + 18v to V+

Slowly turn the Vr1 ccw until the iron bar is drawn into the coil

Record the current value indicated by the ammeter.

I = 0.12 A

Turn off the power and turn the voltage control to the left completely

4. Turn on the power

Slowly raise the positive power until the iron bar is drawn into the coil

Record the values of the power voltage and the current

E = 11.11 V

I = 0.08 A

EXPERIMENT 8-2 : FLEMING’S RULE

PROCEDURES & RESULT

1. The module KL-13005 on the main unit KL-21001, and locate the block a.

2. According to figure 8-5 & 8-6, comlete the experiment circuit with short-

circuit clips Apply+5v to V+

3. Press SW1 and observe the movement of the wire.

What is the direction of the movement ?

The wire move downward

4. According to figure 8-7 & 8-8, complete the experiment circuit with

shortcircuit clips

5. Press SW1 and observed the movement of the wire.

What is the direction of the movement ?

The wire move upward

6. Locate the block b and complete the experiment circuit of figure 8-9.

7. Slowly raise the positive power (+10V) and observe the brightness of the lamp

is the brightness increased as the power is increased ?

YES

DISCUSSION

WHAT IS A MAGNET IC FIELD?

Magnetic fields, like gravitational fields, cannot be seen or touched. We can feel the

pull of the Earth’s gravitational field on ourselves and the objects around us, but we

do not experience magnetic fields in such a direct way. We know of the existence of

magnetic fields by their effect on objects such as magnetized pieces of metal,

naturally magnetic rocks such as lodestone, or temporary magnets such as copper

coils that carry an electrical current. If we place a magnetized needle on a cork in a

bucket of water, it will slowly align itself with the local magnetic field. Turning on

the current in a copper wire can make a nearby compass needle jump. Observations

like these led to the development of the concept of magnetic fields.

CONCLUSION

High magnetic field science and technology are thriving in the United States

today, and the prospects are bright for future gains from high-field research.

High magnetic field science is having an important impact in many disciplines,

including medicine, chemistry, and condensed-matter physics. Recent

accomplishments include the development of functional magnetic resonance imaging

(fMRI), which is revolutionizing neuroscience; optically pumped magnetic resonance

techniques, which allow visualization of new quantum phenomena in semiconductors;

and ion cyclotron resonance mass spectroscopy, which is becoming an important tool

for exploring the chemical composition of complex systems. High-field research has

led to the discovery of new states of matter in low-dimensional systems, and it has

also provided the first indications of how high-temperature superconductors evolve

into unconventional metallic alloys in the extreme quantum limit. Improvements in

ancillary instrumentation and the development of new strategies for using high-field

magnets have contributed to these advances and should continue to do so.

Outstanding work continues to be done in the area of magnet engineering, the

discipline on which all these other activities depend.

REFERENCES

1. Lab sheet 8

2. Magnetism and Magnetic Materials. J.M.D.Coey. April26,2010.

3. http://www.ucpress.edu/content/chapters/11183.ch01.pdf

4. http://www.nap.edu/openbook.php?record_id=11211&page=103

APPENDIX