Question

A voltmeter has a sensitivity of 1000 Ω/V reads 200 V on its 300 V scale. When connected across an unknown resistor in series with a millimeter, it reads 10 mA. The error due to the loading effect of the voltmeter is (a) 3.33% (b) 6.67% (c) 13.34% (d) 13.67% I got this question by my school teacher while I was bunking the class. My doubt stems from Advanced Problems on Two Port Network topic in portion Two-Port Networks of Network Theory Select the correct answer from above options network theory questions and answers, network theory questions pdf, network theory question bank, network theory gate questions and answers pdf, mcq on network theory pdf, gate network theory questions and solutions, network theory mcq Test , ies network theory questions, Network theory Questions for GATE EC Exam, Network Theory MCQ (Multiple Choice Questions)

Answer 1

The correct option is (b) 6.67% The best explanation: RT = \frac{V_T}{I_T} VT = 200 V, IT = 10 A So, RT = 20 kΩ Resistance of voltmeter, RV = 1000 × 300 = 300 kΩ Voltmeter is in parallel with unknown resistor, RX = \frac{R_T R_V}{R_T – R_V} = \frac{20 ×300}{280} = 21.43 kΩ Percentage error = \frac{Actual-Apparent}{Actual} × 100 = \frac{21.43-20}{21.43} × 100 = 6.67%.