Labs and Safety
I am a strong believer in learning by doing. However, doing is sometimes a little more dangerous than not doing. That is why we have to talk about lab safety before we start. We are only dealing with batteries and some static electricity, nothing that you have not encountered before. But shortcircuiting a battery can cause a fire, or touching your precious iPhone or laptop, while statically charged, might be the end of it. That is why we need to be aware of lab safety.
- Static electricity, touch a large metallic object, like a water pipe, or a radiator. static discharge
- large capacitors are potentially dangerous
- periodically check batteries to make sure they are not hot
- always disconnect your circuits from the battery or power supply before you leave your workbench
- if you smell anything, remove the batteries and recheck your circuit
- don't connect power to a circuit until it is completely finished. double check your circuit before connecting it to a battery or power.
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Safety
Safety comes first. Some of the experiments can be dangerous or harmful, they are marked with the label "Instructor". Those are potentially harmful experiments, that should only be done by your instructor or under the direct supervision of your instructor. Especially, people with a heart condition, should be extremely careful. Please let your instructor know if you have or suspect a heart condition.
We will only be working with 9 volt batteries, and those are completely safe, if used properly. Dangerous is anything that has to do with regular electric outlets of 110 or 220 volts: even currents as small as 50-100 mA can trigger cardiac arrest [1]. Also dangerous could be static electricity [3]. So again, any of those experiments marked with "Instructor" should be done by your instructor. If through your actions you put others or yourself in danger, disciplinary measures will be administrated. Never perform any unauthorized experiment.
Although a 9V battery may seem pretty harmless, if used in the wrong way, it can cause a fire. Hence, always follow these simple rules:
- if it starts smelling, disconnect the battery!
- if it starts smoking, disconnect the battery!
- if the battery gets hot, disconnect the battery!
- never leave electric circuits unattended, always make sure you disconnect the battery, before leaving the table or the room.
In addition being harmful to people, electricity can also be harmful to equipment. We expect you to perform all experiments in a serious and professional manner. Some of the equipment is rather sensitive. You are expected to treat all the equipment provided with care.
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Preparations
In the labs you will work in teams of two students. You will perform experiments and write down the results of these experiments in your laboratory notebook. Labs will require preparations beforehand, usually given as an assignment. In case you have not done the preparation, you are not permitted to perform the lab. Your instructor will check that you made the neccessary preparations before you are allowed to perform any of the experiments. At the end of the labs, your instructor will wittness and sign your entries, like it would be done in a real industrial laboratory. Your laboratory notebook is the only proof that you performed the labs, hence do not loose it.
Before attempting to perform any of the experiments in this lab, you need to have done the following preparations beforehand:
- You should know what to do in case of an emergency [2].
- You should know about the dangers of static electricity to people and equipment. (Look for "dangers of electrostatics" on Google.)
- You should know what a short-circuit is, and why it is dangerous.
In addition you should familiarize yourself with the laboratory notebook how to set it up, how to use it, and why it is important. For this please read [4,5].
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Laboratory Notebook
You are expected to keep notes of all the experiments you perform in your laboratory notebook. To see examples on how this is done properly, you should read reference [4]. We want to follow reference [7] for the outline of our experiments, which means, all experiments should include:
- Title: The title should be short and descriptive.
- Hypothesis: Briefly describe the intended experiment and what you expect the outcome to be.
- Materials: List the materials needed to perform this experiment.
- Procedure: In the procedure you describe the experiment in a step by step fashion. This should be brief, but contain enough information, such that somebody else, with your knowledge, can repeat the experiment and verify it.
- Observations & Results: What did you observe and what were the results of the experiment. Not all experiments work perfectly, sometimes they don't work at all. Truthfully describe your observations.
- Conclusion: You started out with a hypothesis, in the conclusion section you either verify or falsify your hypothesis. In the scientific method [8], both are equally important.
In case you are interested to learn how laboratory notebooks are used in industry, we refer you to references [5,6].
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Further Reading
You first must read reference [1] on "Electrical cardiac injuries". Even currents as small as 50 to 100 mA can trigger cardiac arrest, also take a look at table 1 in this reference. It also is required that you read reference [2] on what to do in case of an emergency. If you care about your equipment, like your smartphone and your laptop, then reading the article on "Static electricity and people" [3] might be very enlightening. For German readers the question why the Wikipedia has no German article for the scientific method [8] should be interesting to ponder about.
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Questions
Before you are allowed to perform any of the experiments, your lab instructor will make sure that you have read references [1] and [2], and will ask you questions about it. In case you can not anwer any of those questions correctly, you will not be permitted to take part in the labs.
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What should you do when smoke appears?
- What do you do if you suspect somebody is connected to 220 volts?
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References
[1] Electrical cardiac injuries: current concepts and management, Victor Waldmann, Kumar Narayanan, Nicolas Combes, Daniel Jost, Xavier Jouven, Eloi Marijon, European Heart Journal, Volume 39, Issue 16, 21 April 2018, Pages 1459–1465, https://academic.oup.com/eurheartj/article/39/16/1459/3746021
[2] Emergency Response Chapter 3 - Electrical Safety, www.allaboutcircuits.com/textbook/direct-current/chpt-3/emergency-response/
[3] Static electricity and people, Niels Jonassen, https://incompliancemag.com/article/static-electricity-and-people/
[4] Instructions for Using Your Laboratory Notebook, IW Hunter and BJ Hughey, web.mit.edu/me-ugoffice/communication/labnotebooks.pdf
[5] How to Start–and Keep–a Laboratory Notebook, www.iphandbook.org/handbook/ch08/p02/
[6] Guidelines for Keeping a Laboratory Record, David R. Caprette, abacus.bates.edu/~ganderso/biology/resources/Lab_notebook_guidelines_DR_Caprette.pdf
[7] How to record an experiment, elementalscience.com/blogs/news/how-to-record-an-experiment
[8] Scientific method, https://en.wikipedia.org/wiki/Scientific_method
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