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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

what is tail to tail method
Thobile Reply
a person was standing in a stationary lift / elevator and scale shown is 490N and then 470N when the lift started to move. Did the lift go up or down?
Kamva Reply
down
Fabzeey
How do you state snell's law
Mlondi Reply
The ratio of the sine of the angle of incidence in one medium to the sine of the angle of refraction in the other medium is constant
Boss
who was the first person to discover nuclears bomb
Ismael Reply
how to calculate resistance in grade 11
Ngomane Reply
last year memo in 2018 June exam
Ngomane
can I have last june question paper2
Mike
yes
Ismael
hello
Amanda
hello
Patricia
is there any physics e-copy textbooks?
Patricia
states the Newton's second law of motion
Shallin Reply
In words it says:" when a net force is applied to an object of mass, It accelerates in the direction of the net force. The acceleration is directly proportional to the net force and inversely proportional to the mass".
Buhle
And in symbols: Fnet = ma
Buhle
thank you
Shallin
pleasure
Buhle
hello everyone
Ngomane
hello
Mzondi
hlw
manu
which degree is usually be a refractive angle before it complete a totally reflection?
Mzondi
90°
Boss
yes obviously 90 degree
manu
fnet=ma
Fabzeey
how does hydrogen bonds differ from London force
Madzivha Reply
Hydrogen bonds are the strongest intermolecular forces and London forces are the weakest. Hydrogen bonds exist between polar molecules ( they are a special case of dipole-dipole forces ), while London forces occur between non-polar molecules.
Kagiso
how come the resultant force is 0
Andrew Reply
It's when you have equivalent forces going different directions then your resultant will be equal to zero
Temosho
describe what john's experiment proves about water molecules?
Fanozi Reply
Newton's first law of motion
Ayabonga Reply
hy
Madzivha
hello
Ayah
hey
Dire
hey
Precious
am great n u
Precious
great
Dire
An unknown gas has pressure,volume and temprature of 0.9atm,and 120°C.how many moles of gas are present?
Chrislyn Reply
Can you, if possible send me more quizzes
Bradley Reply
What is selmon
heath Reply
how long it takes for 25ml ethanol to be evaporated?
Kgaugelo Reply
how to calculate acceleration
Sphe Reply
It depends
Mbongeni
Please state the Newton third low
Malwandla
hy
Nelito
Newton's Third law states that to every force applied, there's an equal but opposite reaction
Lala

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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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