Three resistors R₁ = 3 kΩ, R₂ = 2 kΩ and R₃ = 5 kΩ have been connected to a constant current source as shown in the figure. The current source supplies current I = 2 mA to the circuit. A voltmeter with Rᵥ = 6 kΩ internal resistance is connected, as shown, to measure the potential difference across R₁.

Question

G1 Physics · Accepted Answer

Image The voltmeter loads R₁: R₁||Rᵥ = 3||6 = 2 kΩ. Use current division with the surrounding network to compare loaded V₁ with the ideal value. The error is 25%. Interchanging R₂ and R₃ changes the Thevenin resistance seen by the voltmeter so loading becomes more significant; percentage error increases.