Complete question:
An ideal measuring device is one that does not alter the very measurement it is meant to take. Therefore, in comparison with the resistance being measured, the resistances of an ideal ammeter and an ideal voltmeter must be, respectively: Select the best answer from the choices provided.
a) very small; very small
b) very large; very small
c) very small; very large
d) very large; very large
Answer:
c) very small; very large
Explanation:
Ammeters can be said to be a device which measures the flow of electric current through a conductor. An ideal ammeter is said to have zero internal resistance. This is because there will be little or no voltage drop as electric current flows through it.
Therefore the resistance of an ideal ammeter must be very small.
A voltmeter can be said to be a device that measures the difference in potential difference between two points in a given circuit. The internal resistance of a voltmeter is said to be infinite, which means it could be very large. This means no current will flow through the voltmeter and the measured voltage will have little or no error.
Therefore the resistance of an ideal voltmeter must be very large.
