Video: Identifying Circuit Symbols

The diagram shows four circuit symbols. Which symbol represents a variable resistor?

01:15

Video Transcript

The diagram shows four circuit symbols. Which symbol represents a variable resistor?

We see here the four symbols shown. And we’re told that one of them represents a variable resistor in a circuit. Recalling what circuit symbols mean is really a memorization task. Let’s just start from the top and remember what each of these symbols represents.

Option A shows us the symbol for an electrical fuse. This is a device used to limit the maximum current running through a circuit. In option B, we recognize the shark-tooth pattern of this symbol, telling us that it’s a resistor. Option C is like option B. But we see it has the additional diagonal arrow running through the resistor. That tells us that the value of this resistor can be varied. It’s a variable resistor. Option C is our answer then. This shows us the symbol for a variable resistor.

Just out of interest though, let’s consider what option D shows us. We see that sometimes a resistor is represented using this box and sometimes it’s represented using the shark-tooth pattern. The representations are equivalent. And which one we use just depends on which convention we’ve learned. In any case, this line with a slant to it going through the resistor indicates that this is a thermistor, a resistor whose resistance depends on temperature. Our answer though is answer option C. This is the symbol that represents a variable resistor.

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