What steps can be taken to reduce the effect of environmental inputs in measurement systems?  (a) Why is there an error in the measured voltage when a voltmeter is inserted into an electrical circuit...

What steps can be taken to reduce the effect of environmental inputs in measurement

systems?

 (a) Why is there an error in the measured voltage when a voltmeter is inserted into

an electrical circuit to measure the voltage across a component in the circuit?

(b) The voltage across a resistance R5 in the circuit of Fig. 3.10 is to be measured

by a voltmeter connected across it.

(i) If the voltmeter has an internal resistance (Rm) of 8950U, what is the measurement error?

(ii) What value would the voltmeter internal resistance need to be in order to

reduce the measurement error to 0.5%?