Question

The resistance of an ammeter is $13\Omega$ and its scale is graduated for a current upto 100 amps. After and additional shunt has been connected to this ammeter it becomes possible to measure currents upto 750 amperes by this meter. The value of shunt-resistance is-

• A. $2K\Omega$
• B. $20\Omega$
• C. $2\Omega$
• D. $0.2\Omega$

Answer 1

The correct option is C $2\Omega$

Let the shunt resistance be $S$

Given data:

$I=750A,$

$I_g=100A,$

$R_G=13\Omega ,$

From the figure,

$I_g{R}_G=(I-I_g)S$

or $100\times 13=[750-100]S$

or $1300=650S$

$\therefore S=\frac{1300}{650}=2\Omega$