why should an ammeter have low resistance?

John's answer does not make sense.

Contrary to the voltmeter, the ammeter must be put in series in order to measure the current. Again, considering Kirchhoff's Laws about voltage, we don't want the ammeter to affect the current flowing in the circuit. Therefore, we give it a very low resistance, so that the potential difference across the ammeter will be *zero*.

Ammeter Resistance

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RE:

why should an ammeter have low resistance?

if there is large resistance in ammeter so its oppose the flow of current ,it means we can not measure the current under measurement with accuracy because in this condition the measured current is always less than its true value.

thats why we use the low resistance in ammeter.

An ammeter with low resistance could burn out if there is enough current flowing through it.