Question

A 50 V range voltmeter is connected across the terminals A and B of the circuit shown in figure below. If the voltmeter resistance is $1000k\Omega$, then the loading error is

• A. -9.1%
• B. -8.1%
• C. -7.1%
• D. -6.1%

Answer 1

The correct option is A -9.1%

Let us reduce the circuit to its Thevenin's equivalent. The open circuit voltage $E_0$ appearing across terminals A and B is $E_0=50V,$


Voltage appearing across terminals A and B under loading conditions is

$E_L=\frac{50}{1+\frac{100}{1000}}=45.45V$

% loading error

$=\frac{45.45-50}{50}\times 100=-9.1\%$