As shown in the figure, the voltmeter reads 2 V across the 5 Ω resistor. The resistance of the voltmeter i $s ______$ Ω.

Question

As shown in the figure, the voltmeter reads 2 V across the 5 Ω resistor. The resistance of the voltmeter i s ______ Ω.

G1 Physics · Accepted Answer

The voltmeter reads 2 V across the 5 Ω branch. Therefore current through the 5 Ω resistor is I = V/R = 2/5 = 0.4 A Using this current and applying Kirchhoff's current law and voltage law to the remaining branches shown in the figure gives the current through the voltmeter branch. The voltmeter resistance is then obtained from R(V) = V/I(V) which gives R(V) = 20 Ω Final value: 20