(a) Why is there a measurement error when an ammeter is inserted to measure the current in a branch of a circuit? (b) In the circuit shown in Fig. 3.2, the current flowing between A and B is measured...

(a) Why is there a measurement error when an ammeter is inserted to measure the

current in a branch of a circuit?

(b) In the circuit shown in Fig. 3.2, the current flowing between A and B is

measured by an ammeter whose internal resistance is 85 U. The resistance

values are given by:

R1 ¼ 300U; R2 ¼ 200U; R3 ¼ 500U; R4 ¼ 150U; R5 ¼ 500U:

What is the measurement error caused by the insertion of the measuring instrument

into the circuit?