Question

The percentage error in measuring the voltage across a resistor r by a voltmeter of resistance r is

Answer 1

Percentage error = [(E - V)/E] x 100%
                            = (v/E)x100%
                            = [r/(R+r)] x 100%    (as  v = Er/(R+r))
                            =(4/504)  x 100% 
                            ≈ 0.8%