explain how the requirements of high resistance for a voltmeter and low resistan

Question

explain how the requirements of high resistance for a voltmeter and low resistance for an ammeter help minimize the intrinsic error associated with the measurement indicated in figure 2.

e point. The particulul Valuu as the reference point and its value f the battery or of the PS is designated value Ps 0.1 ring circuit indicating the meters explicitly is shown in Figure 2 below. In er measures the potential difference the potential difference across the Vod, PS II Ammeter Measurement of current and voltage. in Figure 2, the ammeter measures the current drawn from the battery whic rough the unknown resistor plus the current through the voltmeter. read the current when the voltmeter is not in use. Then disconnect the a he potential difference across the unknown resistor. Even then, you still w eadings since the meters influence the circuit. He there is ll be a built-in so minimized in the next experiment by using a s b

Explanation / Answer

from the given data

the current flowing through the resistor when there is no ammeter,

I = Vab/Rx

let Ra is the resistance of the ammeter,
the current flowing through the resistor when ammeter is connected,

I' = Vab/(Rx + Ra)

when, Ra = 0

I' = Vab/Rx

= I

That means an ideal ammeter should have zero resistance.

let Rv is the resistance of the voltmeter.
when voltmetere is not connected net resistance of the ckt, Rnet = Rx

when volt meter is connected net resistance of the ckt, Rnet = Rx*Rv/(Rx + Rv)

if Rv >> Rx

Rnet = Rx*Rv/Rv

= Rx

so, an Ideal voltmenter should have infinite resistance not to affetc the ckt.

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