Measure a value: Experimental research (I)
Investigation on the factors that affect the storage capacity of Leyden Jars
Procedures
1. Ensure that the weather isn’t too humid in the morning (that it hasn’t rained a few hours before)
2. Turn the air-conditioner on in the room at full blast and wait until the afternoon (end of school)
3. Set up the experiment as shown in the diagram above
4. Start up the Van de Graaff generator
5. Wait for a period of 5 minutes while the Van de Graaff generator charges the Leyden jar
6. Stop the Van de Graaff generator
7. Measure the amount of short circuit voltage in the Leyden Jar with a multimeter at 1000 setting and get the reading every 10 seconds
8. Repeat Steps 3-7 a total of 3 times and get 3 average values from all the readings
9. Repeat the experiment with a similar setup but with a different jar with different attributes (concentration of salt and/or amount of surface area
Risk Assessment and Management
1. List/identify the hazardous chemicals, activities, or devices that will be used.
We are going to utilise Leyden Jars, Van de Graaff generators and wires. If electricity is handled improperly, the high voltage that can be stored in the leyden jars can cause serious injury and can potentially electrocute someone or destroy expensive research equipment.
3. Describe the safety precautions and procedures that will be used to reduce the risks.
We will wear insulating/safety gloves that protect against electrocution or simply being more careful handling items that contain/generate electricity. Do not touch water or any liquids during experiment. We will ensure that distance is kept from potentially hazardous equipment to prevent burns from overheating of equipment or arcing electricity(if applicable). We will make sure the experiment is conducted in a dry environment. Leyden Jars, if constructed in appropriate size and manner, can deliver a fatal shock. We cannot build jars larger that 30x30 cm approx. else it would be lethal.
Risks in usage of Van de Graaff generator
1. Plug the generator into a grounded (3-prong) 220 volt 50 Hz outlet only.
2. Do not operate in a wet or damp location or outdoors (to avoid shock).
3. Check for loose, worn or frayed wires. Replace any defective parts. (See parts list).
4. Since discharge of electricity can damage electronic devices, keep away from appliances such as televisions,
computers, stereos, microwave ovens.
5. The shock caused by touching the generator directly is not harmful and is similar to the shock received when walking across a carpet and touching a metallic object. It may feel uncomfortable however and should therefore be avoided.
5. List the source(s) of safety information.
Common sources of hazard. In All about circuits. Retrieved July 21, 2013 from http://www.allaboutcircuits.com/vol_1/chpt_3/7.htm
Data Analysis
Tabulate the data for a Leyden jar and then calculate the average amount of short circuit charge that the specific Leyden jar can hold.
Plot 2 graphs, one being the amount of short circuit voltage stored against the concentration of salt in the water in the jar and another being the amount of short circuit voltage stored against the surface area of the jar.
The follow examples of tables and graphs shows how we will record and present our data(Change to concentration in mass)
Concentration
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20g
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40g
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60g
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80g
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100g
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120g
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Voltage at 10sec
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Voltage at 20sec
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Voltage at 30sec
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Voltage at 40sec
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Voltage at 50sec
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Voltage at 60sec
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Area
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Jar 1 (Yellow Cap)
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Voltage at 10sec
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Voltage at 20sec
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Voltage at 30sec
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Voltage at 40sec
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Voltage at 50sec
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Voltage at 60sec
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Bibliography
[2] Wikipedia (2013, JULY 13). Van de Graaff Generator. Retrieved from http://en.wikipedia.org/wiki/Van_de_Graaff_generator
[4] Wikipedia (2013, JULY 13). Static Electricity. Retrieved from https://en.wikipedia.org/wiki/Static_electricity
[6] Wikipedia (2013, JULY 19). Coulomb. Retrieved from
[7] Doan, A (2013, JULY 17). Power your home with LIGHTNING! Retrieved from
[8] Wikipedia (2013, JULY 17). Harvesting lightning energy. Retrieved from http://en.wikipedia.org/wiki/Harvesting_lightning_energy
[9] Dhogal, P (1986). Basic Electrical Engineering, Volume 1. New Delhi: Tata McGraw-Hill.
[10] Mr Solar (2013, JULY 17). Photovoltaic effect. Retrieved from http://www.mrsolar.com/content/photovoltaic-effect.php#.UeYhdGQpYa1
[11] Instructables (2013, JULY 22). How to make leyden jar easily . Retrieved from http://www.instructables.com/id/How-to-make-leyden-jar-easily/
[12] Instructables (2013, JULY 22). Make a Water Leyden Jar . Retrieved from http://www.instructables.com/id/Make-A-Water-Leyden-Jar/
[13] Magnet Lab, National High Magnetic Field Laboratory (2013, JULY 26). Leyden Jar. Retrieved from http://www.magnet.fsu.edu/education/tutorials/museum/leydenjar.html
[14] Wikipedia (2013, JULY 21). Capacitance. Retrieved from https://en.wikipedia.org/wiki/Capacitance
