EMF Essay, Research Paper

To find the factors that affect the amount of E.M.F. being produced. The amount

of E.M.F. produced during the experiment when each type of factors is change.

Background knowledge

Electro-motive-force is the energy being supply to a charge. Battery is a type

of energy. The energy that it provides is voltage. Battery voltage is sometime

called electro-motive-force because it is used to "pump" around the

electrons in the wire. The force can be generates by the moving of magnetic

field as in the left-hand rules (field, current and force). It is the force

that pushes the electrons around the circuit from the positive pole to the

negative pole. That is why current directions in circuits are always marked

from positive to negative.

The voltage of the batteries varies in many volts e.g. 1.5V, 6V etc. A battery

with a voltage of on volt is able to deliver one joule of energy for each

coulomb of charge that passes through it. In other words, the voltage of a

battery is the number of joules per coulomb that the battery can deliver when

it is connected in a circuit.

The law of left-hand rules or Fleming rules is that:

* Thumb is for Motion.

* First finger is for Field.

* Second finger is for Current.

Hypothesis

* Does the change of frequency of the current affect the amount of

electro-motive-force being produced?

* Does the change of current affect the amount of electro-motive-force being

produced?

* Does the number of coil of green wire affect the amount of

electro-motive-force being produced?

* Does the number of coil of wire use for magnetizing the irons affect the

amount of electro-motive-force being produced?

Apparatus

1. AC power supply – provides electricity to the circuit.

2. Signal generator – for providing the electricity the circuit and also for

changing the frequency of the current.

3. Ammeter – for measuring the amount of amp being produced.

4. Coil of wire – produce the magnetic field, which magnetize the pieces of

iron.

5. Two pieces of iron – to be magnetized into a magnet.

6. Circuit wire – for connecting up the circuit.

7. Oscilloscope – for measuring the amount of electro-motive-force being

produced.

8. Green wire – attached to oscilloscope carrying the electro-motive-force to

it to be measure.

Planning

Safety precaution

* Electricity is dangerous therefore be careful while connecting the circuit by

having the power supply turned off at start.

* Wire striper is sharp therefore while stripping careful not to cut your hand.

* Too much current can made the wire to melt causing smoke and fire therefore

tried to use the current as low as possible.

* When magnetizing the iron careful not to put your finger between them because

your finger will either be squash or cut.

Method

First I set up the apparatus as shown above. Then I plug a circuit wire to 0V

and the other to the 2V then I turn on the ammeter follow by the power supply.

I then look at the oscilloscope and measure the width and the height of the

electro-motive-force wave. I record down the result and then I turn off the

power supply. I change the circuit wires now to 0V and 4V. Then I do the same

thing as I did before except that I change the voltage for every experiment

from 0 and 4 to 0 and 6, 0 and 8 and 0 and 12. When I finish all that I have

mentioned I then repeat all of them again in order to get the average results

for each of the experiment.

After I have finished repeating the experiments I then change from AC power

supply to the signal generator. I plug the circuit wire to it and turn it on.

Then after I it on I change the frequency of the current from 0Hz to 10Hz and I

record down the width and the height of the electro-motive-force wave. When I

finished I change the frequency from 10Hz to 20Hz and do the same thing as I

did before except that I change the frequency for every experiment from 20Hz to

30Hz, 40Hz, 50Hz, 60Hz, 70Hz, 80Hz, 90Hz and 100Hz. Then when I finish I repeat

all of them again so that I can get the average results for each of the

experiment.

When I have finished repeating the experiments I then change the signal

generator back to AC power supply. I plug the circuit wires into the power

supply at 0V and 6V but this time I will not vary the current but I will vary

the number of coil of the green wire around the piece iron instead. First I

have no coil around the piece iron and then I turn the power on and record down

the width and the height of the electro-motive-force wave. Then I turn off the

power and add one more coil on to the piece iron and turn the power on. Then do

the same thing as before except that I change the number of coil of wire by

increasing the number by one at the time until it reaches ten coils I stop.

After that I repeat all of the experiment again in order to get the average

results for each of the experiment.

Planning

Factors that will be included in the experiment

* The frequencies of the current that will be vary when it is being tested. It

will be vary every 10 Hz starting from 0 Hz to 100 Hz.

* The current will be varying from the power supply. The current will be 0.25A,

0.5A, 0.9A, 0.11A and 0.31A.

* Number of coil of the green wire will be change from 1 coil to 10 coils.

Prediction

What I have predicted the result will be is that for the change in voltage the

amount of EMF produced will be proportional to the change of the voltage. For

the change in the number of coils I predicted that the change in number of

coils would be proportional to the amount of EMF produced and for the change in

frequency of the current I predicted that as the frequency increased the amount

of EMF produced also increase proportionally.

Evaluation

From the experiments I have done I think that the way I did them is the best

way to carry them out. The method I choose to do to make the experiments as

accurate as possible was to repeat each of the experiments twice. This also

makes it a fair test and it also makes the results more accurate. In my

experiment I do not think there are any errors that have occurred, this is

because that there are no odd results on the graph that would stand out to be

wrong.

If I did the experiment again what I would do is that I would repeat the

experiment on the change of frequency again. But this time with more accurate

signal generator, and small and fine scale of oscilloscope. The other thing I

would do is to do more experiments on other factors as well. For example the

size of the magnet could also be changed, the magnetic field strength could be

changed and the size of green wire could be changed.

Analysis

The best way to make the results become the most effective is to make a record

of the results in the table so that they could be seen clearly and easy to

spot. Also the best way to present the results as clear and as best as possible

is to plot them on to the graph so that they could be seen clearly and easy to

read. The graphs also need the best-fit line to go with them in order to make

it clear for the analysis and to spot any linkage or relationship between the

two sets of results.

Variation on the amount of voltage

From looking at the graph I could see that

Variation on the number of coil

In this variation I decided to change the number of coils around the iron, not

for increasing the magnetic field strength of the iron, and recorded down the

amount of EMF produced. By looking at the graph I could see that as the number

of coils increase the amount of EMF produced also increased. The other word is

that the change of number of coils in proportional to the amount of EMF

produced.

Variation on the frequency

In this variation I decided to change the frequency of the current but not to

change the amount of input current. The amount of current will be the same, in

the experiments I decided to keep it at 0.01 A. From the graph it could be

noticed that as the frequency increased the amount of EMF produced also increased

as well. But at the beginning of the graph from 0 Hz to 10 Hz it could not be

seen clearly though because that the best fit line that was drawn did not go

through the origin therefore it could not be judge that the graph is totally

correct though. This was because that at the beginning it seemed that the graph

started of with the curve and eventually started to become straight line.

The aftermath of the predictions

For the prediction that I have predicted early on, it is indicated from that

results collected, that all the prediction I have made are as expected. For the

induced EMF in every case has changed proportionally to the factors according

to the predictions. This could be seen clearly from the graphs.

Conclusion

What I have found out from the experiments is that for every factors of the

experiment change the same conclusion was found which is that the induced EMF

has change proportionally to the change of factors.

No. of coils Current (A) EFM reading in mV

1st 2nd mean

1 0.03 80 80 80

2 0.04 150 140 145

3 0.04 220 220 220

4 0.04 300 310 305

5 0.04 380 390 385