Question

A galvanometer has coil resistance of $99\Omega$ with full scale deflection current of 0.01A.

• A. With shunt of $11\Omega$ it is converted to ammeter of range 0.1 A.
• B. With shunt of $1\Omega$ it is converted to ammeter of range 1A.
• C. With resistance of $9901\Omega$ in series it becomes voltmeter of range 100 V.
• D. With resistance of $101\Omega$ in series it becomes voltmeter of range 20V.

Answer 1

Answer: (A), (B), (C)

With resistance of $9901\Omega$ in series it becomes voltmeter of range 100 V.


$(I-0.01)r=0.01\times 99$
$(I-0.01)\times 11=0.01\times 99\Rightarrow I=0.1A$

$(I-0.01)\times 1=0.01\times 99\Rightarrow I=1A$

$\Rightarrow V=0.01(R+99)$
$=100=0.01(R+99)\Rightarrow R=9901$
$20=0.01(R+99)\Rightarrow R=1901$