Question

In a parallel combination of two milli-ammeters with full scale deflection 10 mA and 100 mA shows reading of 4 mA and 24 mA respectively. The ratio of their internal resistance will be

• A. 10 : 1
• B. 1 : 10
• C. 6 : 1
• D. 1 : 6

Answer 1

The correct option is A 10 : 1

As the ammeters are connected in parallel,
So voltage is same,

$R_A=\frac{V}{I_{FSD-A}}=\frac{V}{10mA}$

$R_B=\frac{V}{I_{FSD-B}}=\frac{V}{100mA}$

$\frac{R_A}{R_B}=\frac{100mA}{10mA}=\frac{10}{1}=10:1$