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# Physical - Circuit

Extracts from this document...

Introduction

Science Investigation Report        Daniel

F5D

P                O                A                E

6                6                6                4                24/30

Name: Daniel Shih

Class: F5D

Teacher: Dr. Aravind

School: Kiangsu-Chekiang College International Section

Date: 30th November, 2006

Index

Introduction

Planning – Aims, Variables, Fair Test, Prediction, Hypothesis

Planning – Apparatus, Procedure

Planning –Procedure of temperature, measurement, safe rules

Obtaining

Analyse – Table 1

Analyse – Table 2

Analyse – Table 3

Analyse – Table 4

Analyse – Table 5

Analyse – Table 6

Analyse – Table 7

Analyse – Table 8

Analyse – Compare and Contrast

Evaluation, Conclusion, Bibliography

Introduction:

What is an electrical circuit?

An electrical network is an interconnection of electrical elements such as the resistors, inductors and switches. We use circuit to measure the voltage, and also the current of some conductors which can transfer the electricity. To design an electrical circuit, first we need to be able to predict the current and the voltage.

What is electrical resistance?

Electrical resistance is a measure of the voltage divided by the current flows in the electrical circuit. The unit of resistance Is Ohms,Ω. The quantity of resistance in an electric circuit determines the amount of current flowing in the circuit for any given voltage applied to the circuit. The way of measuring the resistance in a circuit is:

“R” is the resistance of the object, measured in ohms.

“V” is the potential difference or the voltage across the object, measured in volts.

“I” is the current passing through the object, measured in amps

So what are the uses of electrical circuit?

This is a test to find out the best conductor in metals, the higher the resistance, that means the better the metal could be used to pass the electrons through.

Also, the temperature of the metal will affect the amount of electrons flows at each time, by heating the metal up, it would expand and allows more resistance; so the temperature were low, it might can’t conduct electricity at all.

Planning:

Aims:

Middle

20

0.3

3.4

0.3

3.5

0.3

3.45

25

0.35

3.4

0.35

3.4

0.4

3.4

30

0.4

3.2

0.4

3.1

0.4

3.1

Length (centimetres)

Voltage (Volts)

Current (amps)

Resistance (Ω)

5

0.1

3.5

0.0286

10

0.2

3.75

0.0533

15

0.25

3.62

0.0691

20

0.3

3.45

0.0890

25

0.37

3.4

0.1088

30

0.4

0.3.13

0.1278

In this graph, we could see that the resistance of the wire were increasing as the length increases. This means constantan wire with diameter of 1.25mm can be use as a good conductor. It nearly occurred in a straight line if the resistance of length 5cm were higher a little bit.

Table 3: This table tells about the normal wires used in the experiment, Constantan wire with diameter of 0.90mm.

 First Tried Second Tried Third Tried Length (centimetres) Voltage (Volts) Current (amps) Voltage (Volts) Current (amps) Voltage (Volts) Current (amps) 5 0.2 3.5 0.1 2 0.1 2.1 10 0.2 1.8 0.1 1.8 0.1 1.8 15 0.2 1.8 0.1 1.75 0.2 1.75 20 0.25 1.7 0.25 1.8 0.2 1.7 25 0.3 1.7 0.3 1.7 0.3 1.7 30 0.4 1.7 0.35 1.7 0.35 1.7 Length (centimetres) Voltage (Volts) Current (amps) Resistance (Ω) 5 0.13 2.5 0.052 10 0.13 1.8 0.0722 15 0.17 1.77 0.0960 20 0.18 1.73 0.1040 25 0.3 1.7 0.1765 30 0.37 1.7 0.2176

In this table, I can see that the resistance weren’t stable. With the length of 20cm, this might because of the ammeter have some problem while we’re measuring. I believe if we have a chance to retry it over again, we should get better results as what we have expected.

Table 4: This table shows about the normal wires used in the experiment, Constantan wire with diameter of 0.90mm, however is longer than the one before. Error*

 First Tried Second Tried Third Tried Length (centimetres) Voltage (Volts) Current (amps) Voltage (Volts) Current (amps) Voltage (Volts) Current (amps) 35 0.7 2.6 0.7 2.7 0.7 2.8 40 0.5 2.5 0.7 2.6 0.7 2.6 45 0.5 2.5 0.4 2.6 0.4 2.5 50 0.8 2.2 0.8 2.3 0.8 2.3 55 0.9 2.3 0.9 2.3 0.9 2.4 60 1 2.3 0.9 2.4 1 2.4 Length (centimetres) Voltage (Volts) Current (amps) Resistance (Ω) 5 0.7 2.7 0.26 10 0.64 2.54 0.26 15 0.44 2.54 0.18 20 0.8 2.27 0.36 25 0.9 2.34 0.39 30 1 2.37 0.43

As the table shows above, the resistance of the length 5cm and 10cm were equal, and then it suddenly decreases. This shows there’s an error; I think it happened because we didn’t set our circuit in the correct positon.

Table 5: This table shows the details about normal wires used in the experiment, Constantan wire with diameter of 0.90mm, however is longer than the one before, retry.

 First Tried Second Tried Third Tried Length (centimetres) Voltage (Volts) Current (amps) Voltage (Volts) Current (amps) Voltage (Volts) Current (amps) 35 0.4 1.6 0.4 1.6 0.45 1.6 40 0.45 1.6 0.45 1.6 0.5 1.6 45 0.5 1.5 0.5 1.6 0.5 1.55 50 0.55 1.5 0.55 1.5 0.55 1.5 55 0.6 1.5 0.6 1.5 0.6 1.5 60 0.6 1.45 0.6 1.5 0.6 1.45 Length (centimetres)

Conclusion

Conclusion

In my own opinion, I believe this is quiet a nice experiment, and I also get some good results as well. I’ve found out that my prediction was correct, about the copper wire with a diameter of 90mm will transfer the least energy compare to the rest of the two.

I also learned about the circuit of electricity, I could now tell how the current flowing was, and how it could be measured. By looking at the results I’ve got, I was really please, even though some mistakes happened in the experiment, but we still success to finish our experiment in the time limit, which is such a great thing to celebrate.

Resistor can be use to protect the ammeter, this is a very useful apparatus; I know the ammeter was an important character in the circuit while measuring the resistance. So if the ammeter were damage cause of the flowing current were too high, this will be a very bad news for us. So take care of the equipment is another important thing I learn from this experiment.

If I have a chance to repeat the experiment, I would be likely to set my circuit up just like this time, because there shall be less problems. And I might use the copper wire more often in the circuit, using copper wires it allows more current to pass through compare to the Nicrhome and Constantan wires, which might help in my future life.

Bibliography:

http://en.wikipedia.org/wiki/Series_and_parallel_circuits

http://www.circuitcity.com/ccd/home.do

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