DC+Motor+Generator

**DC Motor Kit Task**


Construct the basic DC Motor using the kit components. You have a choice of insulated wire for the winding of the armature.

Make a note of the wire used and the number of turns. Wire used Number of turns

Insert a picture of your completed motor.

Give a brief description of how the motor was constructed _ WRAPED WIRE AROUND WOOD THING, SOLDERED ENDS TO MAKE COMUTATORS. REMADE HOLDING STAND AND BRUSHES. PUT IT ALL TOGETHER AND BAM A MOTOR Test the operation of the motor using a DC Power Supply. IV DONE THAT Note this initial Speed 2058

Modify your motor to increase its speed. Make a note of modifications made and the final speed.

Modifications TWIDDLED SOME WIRES

Final Speed 2348


 * Operational Theory**

Explain how the following terms relate to your motor.

Permanent magnet

permanent magnets are used in the dc motor construction to rotate the motor through means of magnetic repulsion and attraction.
magnetic field

A magnetic feild is produced between the two fixed magnets as well as around the motor due to the windings becoming electromagnets
lines of force

lines of force are the funny invisible lines that run from the north pole to the south pole of a magnet, these lines are what causes the attraction and repulsion of magnets
magnetic poles

these are usualy the ends of the magnets, they are defined by which way the lines of force flow. the lines flow from north to south, so that defines the poles of the magnet
magnetic flux and flux density

Flux density is a term used to describe how many lines of force is at the poles, the more lines the stronger the magnet

 * Direction of Rotation**

Look at your motor from the commutator end. OK DONE Make a note of the direction of current in the two conductors at the armature end. IT TURNS CLOCK WISE Determine the direction of magnetic field around the conductor LEFT TO RIGHT Make a note of the direction of rotation and determine the polarity of the permanent magnets.

Produce a sketch to show this interaction


 * Change in Direction**

Change the polarity of the supply (leave the magnets in the same position) and note the direction of the motor.

Explain using a diagram why the direction has changed. THE DIRECTION REVERSES CAUSE THE ELECTROMAGNETIC FIELD IS REVERSED
 * Electromagnet**

The armature is acting as an electromagnet. SURE IS Another example is shown below. I SEE THAT Explain the operation of the electromagnet and determine its polarity. Indicate the North and South pole on the magnet. THE NORTH POLE IS ON THE LEFT AND THE SOUTH ON THE RIGHT IF YOU ARE TO SLOW TO WORK THAT OUT BASED ON THE POSITION OF THE NORTH POLE. THE ELECTROMAGNET CREATES A MAGNETIC FEILD WHEN THE SWITCH IS CLOSED ALLOWING FOR CURRENT TO FLOW.


 * Operation of electromagnet _ refer to right hand grip rule**




 * DC Motor Operation**

Explain the operation of the simple DC motor. Use sketches to show the permanent magnet, loop of wire, two segment commutator and brush assembly. Ensure that you explain how the direction of force is determined.

The following picture shows the principle of the DC Motor



The diagram shows the permanent magnets either side of the armature. The loop of wire that is the armature goes in on the left hand side and comes out on the right. This gives us a clockwise magnetic field around the left hand conductor and an anti-clockwise one on the right. The ends of the armature wire form a 2 segment commutator and on this sits two wires which represent the brushes. As the motor turns the armature 'brushes' against the wire contact.

The main magmetic field interacts with the field of the conductor and produces force. This force is up on the left and down on the right. This forces the motor armature to turn clockwise.

If we reverse either the main field or the direction fo the current going into the armature the motor will spin in revcerse. Change both and the motor will continue in the same direction.


 * Operation of DC Motor**


 * Generator.**

Find a partner and pair up the machines into a motor – generator set. They need to be mechanically coupled so that the motor will drive the generator.

Insert a picture here of your generator

Connect a voltmeter to the generator output and determine the voltage produced.

Voltage

Modify your generator set to increase its speed and output voltage.

Make a note of modifications made

Re-test your motor and make a note of its maximum voltage _

State how Fleming's right-hand rule can be used to determine the induction of an e.m.f. in a conductor being moved in a magnetic field.

Determine the direction of induced emf in your generator set. Record the result here

Reverse the supply and record the induced emf

Describe the operation of the simple d.c. generator with the aid of a sketch. Ensure that you refer to the permanent magnet, loop of wire, two segment commutator and brush assembly.


 * DC Generator**


 * Associated Questions**

State Faraday’s Lawrelating to electromagnetic induction

State Lenz’s laws relating to electromagnetic induction

Explain the transformer principle in terms of induced e.m.f. resulting from changing flux between two coils

Explain, with the aid of a diagram, the operation of the following in terms of electromagnetic principles.


 * Loudspeaker**


 * Electric Bell**