Explain why a variable resistor is used in the circuit instead of a fixed circuit?

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1 Answer
Douglas K.
Jan 31, 2018

The designer wanted to be able to use the variable resistor to vary the output voltage to a desired value.

Explanation:

The equation of the output voltage is:

#V_"out" = R_2/(R_1+R_2)V_"in"#

Please observe that, if the input voltage is held constant, then output voltage largely depends on the value of #R_2#.

An application of this may be where the input voltage is unpredictable (within a range) and the user requires an given voltage. The user can use the variable resistor to set the output voltage to the desired value.

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