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The Right Hand Rule.

Case study : the right hand rule

Use the Right Hand Rule to draw in the directions of the magnetic fields for the following conductorswith the currents flowing in the directions shown by the arrows. The first problem has been completed for you.

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Experiment : magnetic field around a current carrying conductor

Apparatus:

  1. one 9V battery with holder
  2. two hookup wires with alligator clips
  3. compass
  4. stop watch

Method:

  1. Connect your wires to the battery leaving one end of each wire unconnected so that the circuit is not closed.
  2. One student should be in charge of limiting the current flow to 10 seconds. This is to preserve battery life as well as to prevent overheating of the wires and battery contacts.
  3. Place the compass close to the wire.
  4. Close the circuit and observe what happens to the compass.
  5. Reverse the polarity of the battery and close the circuit. Observe what happens to the compass.

Conclusions:

Use your observations to answer the following questions:

  1. Does a current flowing in a wire generate a magnetic field?
  2. Is the magnetic field present when the current is not flowing?
  3. Does the direction of the magnetic field produced by a current in a wire depend on the direction of the current flow?
  4. How does the direction of the current affect the magnetic field?

Case study : magnetic field around a loop of conductor

Consider two loops made from a conducting material, which carry currents (in opposite directions) and are placed in the planeof the page. By using the Right Hand Rule, draw what you think the magnetic field would look like at different points around each of the twoloops. Loop 1 has the current flowing in a counter-clockwise direction, while loop 2 has the current flowing in a clockwisedirection.

If you make a loop of current carrying conductor, then the direction of the magnetic field is obtained by applying the RightHand Rule to different points in the loop.

If we now add another loop with the current in the same direction, then the magnetic field around each loop can be added together to create a stronger magnetic field. A coil of many such loops is called a solenoid . The magnetic field pattern around a solenoid is similar to the magnetic field pattern around the bar magnet that you studied in Grade 10, which had a definite north and south pole.

Magnetic field around a solenoid.

Real-world applications

Electromagnets

An electromagnet is a piece of wire intended to generate a magnetic field with the passage of electric current through it.Though all current-carrying conductors produce magnetic fields, an electromagnet is usually constructed in such a way as to maximizethe strength of the magnetic field it produces for a special purpose. Electromagnets are commonly used in research,industry, medical, and consumer products. An example of a commonly used electromagnet is in security doors, e.g. on shop doors which open automatically.

As an electrically-controllable magnet, electromagnets form part of a wide variety of "electromechanical" devices: machines that produce a mechanical force or motion through electricalpower. Perhaps the most obvious example of such a machine is the electric motor which will be described in detail in Grade 12. Other examples of the use of electromagnets are electric bells, relays, loudspeakers and scrapyard cranes.

Experiment : electromagnets

Aim:

A magnetic field is created when an electric current flows through a wire. A single wire does not produce a strong magnetic field,but a wire coiled around an iron core does. We will investigate this behaviour.

Apparatus:

  1. a battery and holder
  2. a length of wire
  3. a compass
  4. a few nails

Method:

  1. If you have not done the previous experiment in this chapter do it now.
  2. Bend the wire into a series of coils before attaching it to the battery. Observe what happens to the deflection of the needle on the compass. Has the deflection of the compass grown stronger?
  3. Repeat the experiment by changing the number and size of the coils in the wire. Observe what happens to the deflection on the compass.
  4. Coil the wire around an iron nail and then attach the coil to the battery. Observe what happens to the deflection of the compass needle.

Conclusions:

  1. Does the number of coils affect the strength of the magnetic field?
  2. Does the iron nail increase or decrease the strength of the magnetic field?

Magnetic fields

  1. Give evidence for the existence of a magnetic field near a current carrying wire.
  2. Describe how you would use your right hand to determine the direction of a magnetic field around a current carrying conductor.
  3. Use the Right Hand Rule to determine the direction of the magnetic field for the following situations:
  4. Use the Right Hand Rule to find the direction of the magnetic fields at each of the points labelled A - H in the following diagrams.

Questions & Answers

examples of soluble substances
Vuyani Reply
The most obvious example of it.. it salt and water where by salt is a solute because it dissolve in water (solvent)... Sugar and rice are example of insoluble because they do not dissolve
Olwethu
a 400 gram package lying on a horizontal surface is aytached to a horizontal string which passes over a smooth pulley.when a mass of 200gram is attached to the other end of the string , the package is on the point of moving . calculate the weight of the package
Luyanda Reply
Assuming zero acceleration then the weight is w= mg which 0.4x9.8 = 3.92N. If you looking for nett F and acceleration in the system then that requires horizontal force and vertical force downwards subtracting upward force. There's no frictional force.
Martin
according to newton's third law of motion,the reaction force to the weight of a book lying on a table is the?
Reality-KiiD Reply
the measure of the refractive power of a medium is called what?
Reality-KiiD
how may i able to understand
Sboniso Reply
what you what to understand
Nka
Try to learn physics language. In other words. If you read magnetic field, to you you have to feel and know what that means to you. If you've played with magnets and put them close, then hold them apart, the force pushing or pulling them is the magnetic force and the area around is th magnetic field
Martin
I've run out of space but begin keeping your own dictionary on physical science. The same would apply to sound, waves, force, acceleration, motion, etc
Martin
definition of an atom
Tumo Reply
How to calculate normal force
Asandile Reply
how do chemical bond
Ndingae Reply
what is resources
Maboni Reply
What Is A Vector?
Rob Reply
A vector is a force with both magnitude and direction
PARTY
what is reduction
Lesego Reply
reduction is the gain of electrons of an atom ; compound or molecule. reduction is also the decrease of the oxidation number of an atom ; compound / molecule.
Omphile
state Newton's second law of motion
Mthobisi
when resultant or net force act on an object an object will accelerate at the direction of the force at an acceleration directly proportional and inversely proportional to the mass
smosh
definition of Monochromatic light
Zolani
what's the difference between reducing and oxidising agent.and. what's the difference oxidising and oxidation number?
black
In Physics, monochromatic describes light that has the same wavelength so it's one colour
ocean_
What does Redox reactins mean?
kholeka Reply
Reaction in which there is transfer of electrons between elements
sibahle
how to calculate a vector
sakhumzi Reply
state Faraday's law in word
Emkay Reply
which rules do you have to follow to identify oxidation numbers
sessy Reply
there are 7 of them > look them up on siyavula textbook physics
Omphile
Where can I get a Siyavula textbook?
Thimna
if possibly ther was a way to send a document I told hv sent it to you
Mhleli
go to siyavula on Google where u can download the textbook
Tatenda
Why do vectors have arrows?
vanessa Reply
vector quantity has both direction and magnitude so arrows illustrate the direction of the vector
Mhleli

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Source:  OpenStax, Siyavula textbooks: grade 11 physical science. OpenStax CNX. Jul 29, 2011 Download for free at http://cnx.org/content/col11241/1.2
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