file_45966.doc - Episode 109 Electrical characteristics In...

This preview shows 1 out of 3 pages.

Episode 109: Electrical characteristics In this episode, students measure the current and voltage characteristics for several components, and identify ohmic and non-ohmic behaviour. Summary Student experiment: Further characteristics. (40 minutes) Student experiment – Alternative version: Further characteristics. (40 minutes) Discussion: The results. (10 minutes) Student questions: On characteristics. (30 minutes) Student experiment: Further characteristics Students determine the V-I characteristics for a carbon resistor, semiconductor diode and filament lamp. This activity is best carried out individually (if space and apparatus allows this) so that each student has to construct and test his/her own circuit. One of the dangers of always working in pairs is that some students who lack confidence in circuit building will always avoid having to do it. This activity gives good practice in building testing and using a circuit designed to measure current and voltage. They will need a reasonable amount of time to set up, check the circuit and begin to take readings. Make sure they all have correct circuits and that their meters are set to appropriate ranges (many take a long time to come to terms with multimeters). I would suggest about 40 min on the practical work itself. This should allow them all to collect data for all three components. Some will work much faster than this so it may be worth having some additional activities available (e.g. the characteristic for thermistor). Data collection can be handled in two ways: Simply record the data into a prepared table, or record directly into Excel or a similar spreadsheet package. TAP 109-1: Electrical characteristics Student Experiment – alternative version 1 0-12 V  DC/AC 4.24 A A 6.15 V V (Diagram: resourcefulphysics.org)
Image of page 1

Subscribe to view the full document.

If you have access to datalogging equipment, this is a good opportunity to get students to set up and record results automatically. If a pc projector is available it is worth collecting one set of data to use at the end of the practical session (you could generate this yourself or else harvest a reliable set from one of the students/groups). TAP 109-2: Electrical characteristics – Datalogging alternative Discussion: The results In either case it is useful to bring the class together at the end of the practical session (say, 15 minutes before the end of the lesson) to discuss results. If you have collected some sample data you can show them how to process this in real time using Excel and a PC projector. Use this to instruct them about trend lines (don’t join the dots and don’t let Excel take over!). For some or all it may be worthwhile to recommend plotting by hand. This may be the first time they have plotted graphs in Physics that include points in more than one quadrant, so this can be illustrated and discussed. Use terms such as ‘ohmic’ and ‘non- ohmic’ and encourage them to do the same. Reinforce the idea that an ohmic conductor is distinguished by a straight-line graph that passes through the origin. Remind them that resistance
Image of page 2
Image of page 3
You've reached the end of this preview.
  • Spring '12
  • Islam
  • Volt, Resistor, Vacuum tube, Electrical resistance

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern