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Resistors
11 questions By Tony R. Kuphaldt
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Question 4 of 11
When a resistor conducts electric current, its temperature increases. Explain how this phenomenon is significant to the application of resistors in electric circuits. In other words, why would we care about a resistor’s temperature increasing?
Also, what does this indicate about the technical ratings of resistors? Aside from having a specific resistance rating (i.e. a certain number of ohms), what other rating is important for proper selection of resistors in electric circuits?
Reveal answerThe heating effect of electricity through a resistance is significant because that resistance may be damaged by excessive temperature. To avoid damage, resistors must be selected to be able to withstand a certain amount of heating.
Notes:Students need to understand that resistance alone does not fully dictate the selection of a resistor for electrical service. Failure to heed the dissipation ratings of a resistor can result in catastrophic failure!
A good follow-up question to this is to ask what the unit of measurement is for this kind of thermal rating.
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Question 5 of 11
Many resistors have their electrical resistance shown by a set of color codes, or “bands,” imprinted around their circumference. A standard color code associates each color with a specific decimal digit (0 through 9). Associate each of the following digits with its respective color:
- 0 =
- 1 =
- 2 =
- 3 =
- 4 =
- 5 =
- 6 =
- 7 =
- 8 =
- 9 =
Reveal answer- 0 = Black
- 1 = Brown
- 2 = Red
- 3 = Orange
- 4 = Yellow
- 5 = Green
- 6 = Blue
- 7 = Violet
- 8 = Grey
- 9 = White
Notes:Several limericks have been invented to remember this color code, most of them “politically incorrect.” I often challenge students to invent their own limericks for remembering this color code, and screen the inappropriate creations from general class discussion.
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Question 6 of 11
Observe the following “4-band” resistors, their color codes, and corresponding resistance values (note that the last color band is omitted, since it deals with precision and not nominal value):
What patterns do you notice between the color codes (given as three-letter abbreviations, so as to avoid interpretational errors resulting from variations in print quality), the resistance values, and the physical sizes of the resistors?
Reveal answerThe first three color “bands” for all these four-band resistors denote two digits and a “multiplier” value, respectively. Physical size has no relation to resistance.
Follow-up question: what does the physical size of a resistor represent, if not resistance?
Notes:The normal way to teach students the resistor color code is to show them the code first, then show them some resistors. Here, the sequence is reversed: show the students some resistors, and have them figure out the code. An important cognitive skill is the ability to detect and apply patterns in sets of data. Exercises such as this help build that skill.
Read more about resistor color codes.
Awesome! job!!!
Informative 😊
https://forum.allaboutcircuits.com/threads/resistor-worksheet-question-8-insufficient-resources.199603/post-1894332
Hi, A query has been raised on the main Forum by a poster, regarding this Article. [ above thread ]. Request clarification.