Faraday\'s Law Induced Currents and Induced Electric Fields- Prelab Name Date La
ID: 1770869 • Letter: F
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Faraday's Law Induced Currents and Induced Electric Fields- Prelab Name Date Lab day & time:- Question: How can a magnetic field produce a current? Part P- 1: The Galvanometer Previously, you have used the built in functions of digital multimeters to serve as a voltmeter or ammeter. In those cases you learned how to avoid damaging the equipment before you started the lab. Therefore, before starting this lab let's investigate how a galvanometer works. A galvanometer is shown in the picture to the right. The galvanometer is designed to measure miniscule values of current and because of that many galvanometers do not have units on their face. Why would it be advantageous, to measure miniscule measure levels of current in this lab. Explain your answer with your knowledge of physics and justify your answer based on what you will be asked to do in this lab. 1. What kind of measurement issues could you have when using a galvanometer? Consider how fast small levels of current might change. Make sure you explain your answer. 2. 3. How could you damage your galvanometer and how could you avoid this? Explain your answer Last Revised 05/26/2015 Faraday's Law 11.1Explanation / Answer
1) If the electric current produced during the experiments is incredibly small, the galvanometer is a useful tool in quantifying this current, no matter how small it may be. This is due to the construction of the galvanometer, where a tightly wound coil is placed in a permanent magnet's uniform field. When current flows through the coil, the magnetic field produced by the coil opposes the permanent magent's field and therefore moves against a spring that is attached to a pointer.
2) A prominent disadvantage of the galvanomemter is that it cannot measure AC current. Also, if the current is a fluctuating current, that is, it changes rapidly in a short period of time, the galvanometer is unable to produce results at such small instances of time, predominantly explained due to: a) the magentic field produced by the coil will not change as rapidly as the current, there may be some decay time; b) the spring itself that is attached to the coil and the needle, may provide some resistance proportinate to the spring constant if it is not allowed to come to rest after each measurement.
3) Damaging a galvanometer is incredibly easy - it is important to make sure that the current passing through the galvanometer is not more than what it's sensitivity values predict. The workaround is to connect a resistor of appropriate value in series combination to allow the large voltage to through around the galvanometer, therefore allowing only a limited current to pass through the galvanometer itself.
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