Galvanometer to Ammeter Galvanometer to Voltmeter

A galvanometer with a coil of resistance 12.0 Ω shows full scale deflection for
a current 2.5 mA. How will you convert the meter into:
(i) An ammeter of range 0 to 7.5 A,
(ii) A voltmeter of range 0 to 10.0 V?
Determine the net resistance of the meter in each case. When an ammeter is
put in a circuit, does it read (slightly) less or more than the actual current in
the original circuit? When a voltmeter is put across a part of the circuit, does it
read (slightly) less or more than the original voltage drop? Explain.


An ammeter of resistance 0.80 Ω can measure currents upto 1.0 A. (i) What
must be the shunt resistance to enable the ammeter to measure current upto
5.0 A? (ii) What is the combined resistance of the ammeter and the shunt?


12.A voltmeter, an ammeter and a resistance are connected in series with a
battery. The voltmeter gives same deflection but the deflection of ammeter is
almost zero. Explain why?