• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# design of a variable resistor

Extracts from this document...

Introduction

International School of Phnom Penh                                                5199

Candidate name: HOZUMI Haruka                                          Page  of

Candidate Number                                                             Science

Design of a Variable Resistor

Aim: Our aim is to find the most suitable length and thickness of wire for the variable resistor with a broken wire. We will determine the difference in resistance between three copper wires with different diameter, and three wires with different lengths (10cm, 15 cm 20 cm).

We chose these lengths. We thought that three different lengths would be enough to

Hypothesis:

Diameter: We think that larger the diameter of copper wire, it will have more resistance because copper wire generally has higher resistance. Since it is largest, it will have more resistance.

Length: We think that the longer the wire, the resistance will be higher because the electricity has to travel longer distance.

We think that

We chose these diameters because

Apparatus:

• Copper wires (3 diameter size, all 10cm)
• Copper wires (3 different lengths – 10cm, 15cm, 20cm)
• Power cell
• Ammeter
• Variable resistor
• Volt meter
• Wires (to connect)
• Scissor
• Ruler
• Calculator
• Crocodile clips

Independent variables:

• Diameter of wires – for testing diameter
• Lengths of wires – for testing lengths

Controlled Variables:

• Length of the wires (for testing diameter) – we will make the wires as straight as we can, and use a ruler to cut them in same size (length). The lengths have to be same because if it is different, the test would not be fair.
• Diameter of the wires (for testing lengths) – we will use the same type (size). The diameters have to be same because if it is different, the test would not be fair.
• All the wires should be straight so that the electricity can travel easy.
• Voltage – we will keep the power cell to 3 V to make the experiments fair.
• Use the same apparatus (variable resistor, ammeter, volt meter) to make the experiments fair.

Dependent variables:

• Resistance - We will measure by using the volt meter and ammeter. We will use the Ohm’s Law (Voltage = Current * Resistance)with a calculator to find the resistance.
...read more.

Middle

0.046

Testing a copper wire with diameter of       3rd experiment

Diameter (   mm)

Ammeter (amp)

Voltage (V)

Resistance (Ohm)

4.7

0.28

0.05957447

4.75

0.28

0.05894737

4.8

0.3

0.0625

Average resistance of the 3 Wires with Different Thickness (Diameter)

 Diameter (mm) Resistance (Ohm) 0.06174412 0.059712123 0.05657483

Difference

mm – mm =0.002031997

mm – mm =0.003137293

Average difference = 0.002584645

Lengths

Testing Copper wire with length of               1st experiment

Lengths (cm)

Ammeter (amp)

Voltage (V)

Resistance (Ohm)

10 cm

4.6

0.3

0.06521739

15 cm

4.65

0.32

0.0688172

20 cm

4.55

0.32

0.07032967

Testing Copper wire with length of                 2nd experiment

Lengths (cm)

Ammeter (amp)

Voltage (V)

Resistance (Ohm)

10 cm

4.7

0.3

0.06382979

15 cm

4.7

0.3

0.06382979

20 cm

4.65

0.32

0.0688172

Testing Copper wire with length of         3rd

...read more.

Conclusion

To improve our methods, we could have used longer wires (for the diameter experiment) to see bigger differences. For the lengths experiment, we could have used three different lengths with more difference. (e.g. 15, 30, 45), also to see larger differences. We also can use ammeter and volt meter with bigger space between each numbers.I think the first suggested improvement, which is to change the lengths of the wires would make more differences in resistances between the three wires. The second suggested improvement, which is to use bigger ammeter/volt meter (ones with bigger space between each numbers) will make the results clearer. It will give the accurate results since it is easier to see.To follow up this investigation, I can now do an experiment with different types of wires (e.g. copper, lead, nickel, etc) to test which type has the highest resistance and which has the lowest.This will be useful. Variable resistors are important since it is used in many places such as in science lab and in household electrical equipments. If we know the resistance of each types of wires, we will know how long or big (thickness) of the wire is suitable for the replacement of the variable resistors. If we know the resistance of different types of wires, we can also find the cost-effective way to make variable resistors.

...read more.

This student written piece of work is one of many that can be found in our International Baccalaureate Physics section.

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related International Baccalaureate Physics essays

1.  ## Experiment to calculate the diameter of a piece of nichrome wire from its electrical ...

3 star(s)

Therefore, the compositions between the metals vary, thus the electrical resistance also vary. Therefore, the median of the range, 1.25x10-6 ?m, will be used. The cross sectional area for a wire is . By substituting this in the equation and simplifying, the equation becomes: If the resistance and length becomes

2. ## To test the ohmic and non-ohmic behavior in a resistor and a bulb

R = 1 3. R = 1 4. R = 1.00 5. R = 1.00 6. 6. R = 1 Discussion: From calculation 1, it is evident that the resistance increases as the current in the circuit increases leading to increase in temperature. On the other hand, fig 1.1 shows a non-linear relationship between voltage and current, which is evidently a non-ohmic behavior.

1. ## Resistance Lab. Aim - To investigate the effective resistance (total resistance) of ...

Now for each value of current separately calculate an average value of the voltages on V1, V2, V3 and Vs. 7) Using the average values of V1, V2, V3 and the value of the current calculate the values of resistance (R1, R2 and R3)

2. ## Investigating Wires

Aim- The aim of this experiment is to primarily investigate how varying the length of a nichrome wire alters it's resistive power. Electrical resistance is a ratio of the degree to which an object opposes an electric current through it.

1. ## Physics IA CE - Investigating the resistance of a wire

0.46 0.44 0.46 0.45 0.30 0.38 0.40 0.40 0.39 1.10 1.20 1.20 1.17 0.38 0.26 0.25 0.27 0.26 1.10

2. ## HL Physics Revision Notes

Outline an application of the use of a laser Technology (bar-code scanners, laser disks) Reading and writing of CD?s G2: Optical Instruments: Define the terms principal axis, focal point, focal length and linear magnification as applied to a converging (convex)

1. ## How does the sinkage depth of a tyre affect its rolling resistance ?

When we talk about the rolling resistance the tire faces on sand , it is important to remember that sand is a loose surface and the tire has the ability to sink in the sand . If a tire sinks in more than its usual sinkage depth .

2. ## Determining the diameter of a piece of Nichrome wire by determining its resistivity

Five trials were taken for five different lengths to obtain a reliable, wide range of data. Safety Precautions: 1. Precaution was taken so that the Nichrome wire would not hurt the finger. 2. Precaution was taken to make sure there were no fire hazards due to short-circuit. • Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to
improve your own work 