### 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.