# Magnetic field associated with a current  (Page 2/2)

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## 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.

## 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 the formula for calculating tension
You can use simultaneous equations or T=mg+ma
sibahle
- Which formula can you use if you want to calculate acceleration?
Pretty
to calculate acceleration you use formula Vf -Vi divided by the time (t)
sholan
What is the formula of calculating tension
I don't think there's a formula u just have to use all information in that type of situation
Gwebzi
can a mixture of atoms make a molecule
define the term "resultant"
the sum of all the forces acting on an object
Think
carring out an investigation of the relationship of acceleration and net force with mass kept constant
Ronald
how to calculate coefficient of kinetic force
kinetic friction × Normal force
Murunwa
how to get a valency electron
how to calculate acceleration due to gravity
how to calculate inertia and it's definition
how to draw a box of tall the force that act on the box mass is 5 .00 and lies a ramp with 30°
how to determine Gravitational acceleration
what is a force
A force is a pull or push action that affects the shape, motion and direction of an object
Chauke
the different types of friction forces
Bhereza
different types of frictional forces are static frictional force(the object is stationery)and kinetic frictional force(the object is moving)
Raymond
static
Dineo
what is a vector
a vector is a physical quantity that have both magnitude and direction
Edith
how to calculate the magnitude and direction if, P=500N,10°,Q=200N,30°,R=300N,60°
Describe relationship between the net force exerted on an object and acceleration of the object in words
Newton's second law of motion states that the acceleration of an object is equal to the net force exerted on the objectdivided by the object's mass. The direction of acceleration is the same as the direction of thenet force.
Sebastian
what is close vector diagram
Lebogang
can you describe the relationship between the netf exterted on an object and A of the object for me plz
Lebogang
the are directly proportional When one increase the other will roo
Gwebzi
too
Gwebzi
and the mass is inversely proportional
Murunwa
what is an intermolecular
is the forces that act in the molecules
Lebogang