A 9.0000-V battery is used to produce a current through two identical resistors in series,each having a resistance of 150.00 k$\varOmega$.A handheld digital multimeter (DMM)is used to measure the potential difference across the first resistor by placing probe leads at each end of this resistor.Typical DMMs have an internal resistance of 10 M$\varOmega$.What is the effective resistance of the circuit with the DMM connected?
A)296.85 k$\varOmega$
B)300.00 k$\varOmega$
C)297.78 k$\varOmega$
D)305.15 k$\varOmega$
E)302.22 k$\varOmega$

Question

Quizplus · Accepted Answer

The effective resistance of the circuit with the DMM connected can be found by adding the resistance of the two resistors in series, and the internal resistance of the DMM in parallel. We can use the formula 1/Req=1/R1+1/R2+1/RDMM, where R1=R2=150.00 kΩ and RDMM=10 MΩ. Substituting the given values, we get 1/Req=1/150.00k+1/150.00k+1/10M. Simplifying this equation, we get Req=297.78 kΩ, which is closest to choice C (297.78 kΩ).

A 90000-V Battery Is Used to Produce a Current Through Two