An ammeter is converted to a voltmeter by

An ammeter is converted to a voltmeter by

Right Answer is:

Putting a large resistance in series with the actual measuring part of the instrument

SOLUTION

An ammeter is used to. measure current in amperes. It is a moving coil galvanometer in which a low resistance wire is connected in parallel.   An ammeter is converted into voltmeter by putting a large resistance in series with the actual measuring part of the instrument.

Let

Vr- Voltage range you required to measure (KNOWN VALUE)

If– Current required to full-scale deflection of your Ammeter (KNOWN VALUE)

Ra- Internal Resistance of Ammeter (Ideally Ra=0)

Rs- Resistance Should be Connected in Series with your existing Ammeter=?

Vr=(Ra Rs× (If)Vr=(Ra+Rs) × (If)

Vr=(Rs×If)Vr=(Rs×If) (We know that Ra=0 )

Rs=Vr/If

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