Electromagnatics experiment on plastic sheet and hair fibre powder...
Electromagnetics Group T8 Muhammad Ramdhan bin Mohd Suhaili Muhammad Nurhidayat bin Muhtaza Muhammad Luqman bin Azmer Muhammad Izzuddin bin Abdullah Abstract-These experiment contain two different cases. Case 1 experiment are to investigate the electrostatic characteristic of the stress film that has been used widely as wrapping material. The electrostatic charge contain on surface of stress film can be harmful to the electronic components. The experiment are successful and the result are same as the theory of electrostatics. There are movement of electron on the surface cause the form of induce charge. While for case 2 experiment, five types of hair fiber were given to find best hair fiber based on their magnetic characteristics. Then a solenoid are used to test each hair fiber by using magnetic field sensor. However based on the formula, the result are varied current values, number of turns and length of wire wrapped used are manipulated. From theory, magnetic field also effect by permeability of magnetic material,µr used. Case 1: Electrostatic for stress film. Introduction Stress film are widely use to wrap the product from factory to avoid from damage. But, electronic components such as IC are very sensitive to the stress film. Electronic component can be easily damage effect of the electrostatics charge on stress film. These task will test two difference condition of stress film which is “rubbed” and “unrubbed” stress film and normal plastic. The induce charge will be measure by using Faraday’s Cage, charge sensor and LabQuest equipment. The charge density can be measure by using specific formula. Procedure. 1. Setup the equipment properly. 2. Firstly, put the metal rod to “clear” the charge inside the Faraday’s cage.
3. The unrubbed stress film was put inside the faraday’s cage. 4. The average reading of the induce charge was collected for 30 seconds. 5. The charge density was calculated by using the formula. 6. The stress film was rubbed slowly for 3 minutes and before put it back inside the Faraday’s cage. 7. Repeat the step 2 until 5. 8. Then, the stress film was rubbed as fast as possible for 3 minutes and put it back inside the Faraday’s cage. Repeat step 2 until 5. 9. Repeat the experiment by using a “rubbed” and “unrubbed” normal plastics. 10. Observe and compare the changes and the differences between all the conditions. Data and Result For “unrubbed” stress film. 0 0
-0.5 -1 -1.5
Time (s) 0 5 10 15 20 25 30
Charge(nC) -1.667 -1.099 -0.755 -0.595 -0.528 -0.531 -0.366
−1.667 − 1.099 − 0.755 − 0.595 − 0.528 − 0.531 − 0.366 7
= -0.792 nC/s
For “slowly rubbed” stress film.
Time (s) 0 5 10 15 20 25
Charge(nC) -1.767 -1.011 -0.7 -0.556 -0.439 -0.4
−1.767 − 1.011 − 0.7 − 0.556 − 0.439 − 0.4 7
−1.767 − 1.011 − 0.7 − 0.556 − 0.439 − 0.4 7
= -0.6961 nC/s
= 0.719 nC/s
For “fast rubbed” stress film.
For “rubbed” normal plastic.
Time (s) 0 5 10 15 20 25 30
Charge (nC) -5.265 -2.837 -1.894 -1.428 -1.192 -1.053 -0.922
−5.265 − 2.837 − 1.894 − 1.428 − 1.192 − 1.053 − 0.922 7
= - 2.084 nC/s For “unrubbed” normal plastic
−1.767 − 1.011 − 0.7 − 0.556 − 0.439 − 0.4 7
= -1.299 nC/s Discussion From table, it shows that the rub stress film give a negative value of induced charge. During the rubbing process the electron from cloth are moving to the stress film.in this case,
stress film gain the electron from the cloth. Therefore the stress film give a negative value. Supposedly, the unrubbed stress film contain a natural charge. It means that the amount of negative charge and positive charge are balance. But the result from the experiment give a negative value. From there, the early conclusion that can be made are the stress film are very sensitive material due to surrounding. Therefore, the stress film are suitable to use as wrapping film for electronic component. The faster the rubbing of the stress film the higher the value of induce charge are produce. When the value of induce charge are high, the value of charge density also high. Here is the comparison of charge density between “fast rubbed” and “slow rubbed” stress film. 𝑄 = 𝜌 ∫ 𝑑𝑆 𝑄=𝜌𝑆 𝑄 𝜌= 𝑆 The surface area for stress film that has been used are: S = ( 3 x 10-2 ) ( 6 x 10-2 ) = 1.8 x 10-3 m2 For “fast rubbed” stress film. 𝑄 − 2.084 nC/s 𝜌= = 𝑆 1.8 x 10−3 𝑚2 = - 1.158 C/m2 For “slow rubbed” stress film. 𝑄 −0.792 nC/s 𝜌= = 𝑆 1.8 x 10−3 𝑚2 = - 440nC/m2 The cloth that used for rubbing the stress film are positively charge based on the graph from LabQuest as shown below. It is because of the electron in cloth are transfer or move to stress film.
Figure 1: charge for rubbed cloth For second experiment, a normal plastic are used for both situations which are rub and unrubbed. The total surface area for these normal plastic are same as the total surface area for stress film. For the unrubbed situation, we put the plastic in the Faraday Cage for about 30 seconds and we record the data. It shows that plastic has positive charge. Then, we rub the plastic for about 3 minutes. Then put it inside the Faraday Cage for about 30 seconds. The result shows that plastic has negative charge in it. As the result, the negative charges are transfer to the plastic during rubbing process. The value of charge of plastics are different from stress film. As the hypothesis, every material has their own properties and amount of charges. Materials also a very sensitive when there is a disturbance. Calculation for normal plastic. To find charge density: 𝑄 = 𝜌 ∫ 𝑑𝑆 𝜌=
“Unrubbed” plastic ρs = 0.719 / 1.8 x 10-3 =399.44 nC/m2 “Rubbed” plastics: ρs = -1.299 / 1.8 x 10-3 =-721.67 nC/m2 From data above, charge density normal plastic are low than stress film stress film and normal plastics are not suitable to use as wrapping film for electronic components because the stress film have high tendency to gain electron. It can gain electron from the
surrounding easily because the stress film are very sensitive material. It very sensitive to the temperature, light and friction. The movement of electron from one material to another material produce electrostatic discharge (ESD). It is result of an unbalanced electrical charge at rest. When static charge moves from one surface to another, it become ESD. The movement of these charges often occurs rapidly and randomly, leading to high current that can damage the components. Case 2: Hair Fiber Introduction Hair powder are being use to make hair to denser. Hair powder stick to hair base on electrostatic principle. The strength of hair powder attract to hair base on its electric charge density. Which is the best hair powder brand base on its electric charge density? A magnetic field is the magnetic effect of electric current and magnetic material. A long straight coil of wire can be used to generate a nearly uniform magnetic field similar to bar magnet. This are basically call solenoid. Solenoid is thin loop wire wrapped around metallic core that will produce magnetic field in a volume space when an electric current pass through it. There are two condition that effect solenoid operation. First, wrapped wire should be insulated by one and another so that less flux loss to the environment. Second, volume of space inside solenoid also effect the magnetic flux flow through it.
1. Measure capacitor cavity radius, r and height, h with ruler and calculate its volume. 2. Fully fill capacitor cavity with hair powder. 3. Record the value of its voltage, V and capacitance, C. 4. Calculate and record the hair powder charge, C charge density, 𝜌𝑉 and dielectric permittivity,𝜖 by using given equation 2 and equation 7. 𝜌𝑉 =
𝐶 , 𝑉
5. Repeat step 1 to 4 by using four different hair powders.(Caution: Capacitor cavity need to be FULLY filled to gain accurate measurement of charges.) 6. Pipe hole first wrapped with long wire and set at number of turns of 15,(N=15). Then measured and recorded. 7. DC power supply was set to supply 1 ampere (1A) of current through wrapped wire. 8. Nanogen type hair fiber insert into whole pipe hole. Then, magnetic field sensor placed in the pipe hole to measure the strength of magnetic field inside the solenoid. Result recorded. 9. Then, amount of Nanogen hair fiber were reduce half from original value. Then, magnetic field sensor are placed again in the pipe hole to measure magnetic field strength. Result recorded. 10. Both result using a type of hair fibre compared. 11. Then, step 1 to 5 are repeated. However, hair fibre types changes by replacing Nanogen with SMH, Toppik, XFusion and Biothik. 12. Lastly, Nanogen hair fibre was insert into pipe hole and turns number, length wrapped wire and current are set as manipulated variable. 13. The result of each experiment recorded.
Data & results Brand
Nanogen XFusion Toppik SMH BioThik
0.57n 0.56n 0.56n 0.58n 0.70n
Hair Fibre Types
Current (A) Number of Turns (N) Length coil (L) Amount Hair Fibre
Air Nanogen SMH Toppik XFusion Biothik
Voltage across cavity, V 27.1m 24.6m 47.8m 41.8m 46.5m
Charge density, 𝜌𝑉
21.03n 22.8n 11.7n 13.9n 15.1n
0.74m 0.81m 0.41m 0.49m 0.53m
Magnetic flux density, β (Tesla) 1 2 15 15 0.034 Small 0.0059 0.3268 0.3427 0.3427 0.3713 0.3669
Volume of capacitor cavity: ⥤ 𝑉 = 𝜋𝑟 2 ℎ V = 𝜋(3𝑐𝑚)2 (1𝑐𝑚) = 28 𝜇𝑚3 3.54 Discussion The higher the electric charge density, the higher the attraction power of hair powder toward hair strand base on electrostatic principle. Dielectric permittivity doesn’t affect the usage of hair powder on hair because dielectric permittivity of medium only affect or is effect by electric field. Dielectric permittivity is almost same for all brands because their capacitance value it almost same. Magnetic field theory stated that: β = µnI where n = N/L and µ = µ0 µr The theory proved. Result shows that magnetic
Large 0.0059 0.3710 0.3408 0.3179 0.3388 0.2866
Dielectric permittivity, 𝜀 2.01n 1.98n 1.98n 2.05n 2.48n
flux density increase when current flow increase and wire turns number increase. However, vacuum permeability at free space recorded some error that may occur in measurements or instruments used. From experiment conducted, the magnetic permeability calculated was µ0 = 13.3733 µ wb. This value differ from the real µ0 which is µ0 = 4π x 10-7 . The result of magnetic flux density was used to calculate magnetic permeability of each hair fiber types. Result are shown in the table below: Hair Fiber Types Air Nanogen SMH Toppik XFusion Biothik
Magnetic Permeability, µr (wb) 13.3733 µ 0.1250 0.1316 0.1316 0.1426 0.1410
The magnetic flux density will be higher if the pipe hole are inserted with high magnetic
permeability materials such as iron, nickel or copper. In real electricity power plant, there will be high magnetic flux produce around the main core because larger value of current used. Based on the experiment results the best hair powder brand is XFusion because it has the highest electric charge density and highest magnetic permeability. Conclusion For case 1, material have their own electrostatic properties. Film without any kind of rub or disturbance will not damage the electronic chip because no electron transfer. When there are electron transfer, there will be increasing negative charge on the film. Then the charge will harm electronic chip. Electronic chip is very sensitive to the disturbance of the charge. For case 2, increasing electric charge density of the powder will make it more stick to the hair. The best hair fiber is XFussion. We use capacitor cavity because we can get more parameters. For magnetostatic part, electromagnetic field strength are affected by strength of magnetic materials used, number turns of wire and amount of current flow through the system. Reference 1. Mathew N.O Sadiku, Principles of Electromagnetics. Oxford University Press, 2009 2. Dessier, RJ (2008), Dipole in Magnetic Field, Physical Review 3. http://www.vernier.com/products/sensors/ crg-bta/ 4. http://en.wikipedia.org/wiki/Magnetostatic s 5. http://en.wikipedia.org/wiki/Electrostatics