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Asked in GUJCET 2014 · Conversion to ammeter and voltmeter
Idea: a voltmeter is joined across the two points whose potential difference is wanted, so it must draw almost no current — its resistance has to be very large.
The coil by itself reaches full scale at only I_gG volt, a tiny range, because its resistance G is small.
Putting a large resistance R in series makes the range V=I_g(G+R), which is large, while the high resistance of the branch keeps the current it takes from the circuit negligible.
Being in series, R still passes the same I_g at full scale, so the meter's scale remains valid.
So a high resistance is connected in series with the coil.
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