Question #c3b78

1 Answer
Jan 29, 2016

Answer:

I would go for B) zero to #7.5V#

Explanation:

The variable resistor can be set (I think) starting at zero up to #50kOmega#.

At zero (basically the resistor becomes a simple wire) the voltage drop between points P and Q is zero (or the difference in potential between them is zero).

When at #50kOmega# we can use Ohm`s Law:
#V=Ri#
to find the current in the circuit comprising the series of the two resistors:
#i=V/R=9/(10kOmega+50kOmega)=1.5xx10^-4A#
and again to find the voltage drop across the variable resistor (at #50kOmega#):
#V_(PQ)=50kOmega*1.5xx10^-4A=7.5V#