Question

Why should the resistance of:
(a). An ammeter is very small
(b). A voltmeter be very large

Answer 1

As we know the resistance is the measure of the opposition to current flow in an electrical circuit. An ammeter is used to measure current and a voltmeter is used to measure the potential difference. Here, we will use these basic concepts to solve the question.

Complete step-by-step solution:
Here, as we know that the resistance is a measure of the opposition to current flow in an electrical circuit. Further, it is measured in Ohms.
Also, resistance depends upon the shape, size of a material.
A). As we know that a resistance opposes the flow of current in a circuit, so, the resistance in an ammeter should be very small because it should not change the value of the current flowing in the circuit, i.e., the current should remain the same it should not vary.
B). Also, we know due to the fact that resistance opposes the flow of current in a circuit, so, the resistance of a voltmeter should be very-large so that it takes a negligible current i.e. if resistance is large the voltage flowing in a circuit will be more and thereby having very less flow of current.
Additional information-
As we know that an ammeter is used to measure the current. The S.I unit of current is Ampere (A). Also, an electric current is a stream of charged particles like electrons, moving through a conductor.
Following is the basic electric circuit diagram having an ammeter, voltmeter, resistance, a key, and a battery.
Further, potential (V) is defined as the amount of work needed to move one unit of electric charge from a reference point to a specific point in an electric field. The voltmeter is used to measure the electric potential difference between two points in an electric circuit. The S.I unit of potential is Volts (V).

Note: Here, we should know that the Current can be measured in different units like micro Ampere, mili Ampere. Potential can be measured in different units like microVolts, milliVolts. In insulators, the flow of current is not possible whereas, in conductors, the flow of current is seen which makes it a good conductor of heat and electricity.