# Comparing circuits question

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#1
I just want to clear my concepts and double check if my thinking process is right. I understand why variable resistor cannot get to zero since minimum resistance possible is the 8k ohm resistor.
Is it that the potential divider can give 0 current because of short circuit when slider goes to A?
And why can the variable resistor give a larger current? Shouldn't the greatest current given by both circuits be the same? (when variable resistor = 0 ohms and when potential slider is at C)

The question:
The 8.0 k resistor is now connected in a circuit with a 4.0 k variable resistor as
shown in Figure 3.
Compare this arrangement for controlling the current in the 8.0 k resistor with the potential divider arrangement in Figure 2

potential divider can provides sensitive control of current (from 0 - 1.1mA) B1
allow pot div can provide zero current and variable resistor gives larger current
variable resistor can provide larger current but cannot get near 0 A

For diagram reference (question 5)
https://www.physicsandmathstutor.com...der%2520QP.pdf
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1 month ago
#2
(Original post by anonymouss2004)
Is it that the potential divider can give 0 current because of short circuit when slider goes to A?
Yes.

And why can the variable resistor give a larger current? Shouldn't the greatest current given by both circuits be the same? (when variable resistor = 0 ohms and when potential slider is at C)
That's not quite true - in the circuit with variable resistor, the same current has to pass through both 8 kΩ resistor and the variable resistor, whereas in the potential divider circuit the current is always split to some extent (unless the potential slider has infinite resistance).
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