Exercise 2. An instrument used to measure current is called an ammeter: The ammeter is connected into a circuit in series in the loop in which the desired current reading is required: The resistance of an ideal ammeter is zero, and it is essential in real ammeters that the R resistance of the instrument be very small compared to other resistances in the circuit_ Why?
A meter to measure potential difference is called a voltmeter: To find the potential difference between two points in a circuit the voltmeter terminals are connected between those two points _ The meter is connected in parallel with the circuit elements between the two points_ The resistance of an ideal voltmeter is infinity, and it is essential in real voltmeters that the resistance of the instrument be very large compared to the resistance f any circuit elements across which it is connected_ Why?
What would be the effect of a voltmeter that was really an ideal ammeter mistakenly connected in parallel?
In the circuit for exercise 2, assume that & 5.0 V,r = 2.0 0, R1 5.0 9, and Rz =4.0 0_ If the ammeter resistance is RA 0.1 9, what percentage error is made in reading the current? Assume the voltmeter is not present for this problem_