Question

The ammeter, shown below, consists of a $ 360\, \Omega $ coil connected in parallel to a $ 40 \,\Omega $ shunt. Find the reading of the ammeter

• A. $ 0.35\,A $
• B. $ 0.4\,A $
• C. $ 0.25\,A $
• D. $ 0.02\,A $

Answer 1

Answer: (D)

As resistance $40\,\Omega$ and $360\,\Omega$ are in parallel, so their equivalent resistance is $360\, \Omega$. Which is further connected in series with $164\,\Omega$.
$\therefore $ Total resistance $= 200\,\Omega$

$\therefore $ current $i = \frac{40}{200} = 0.2\,A$
Now, from $A$ to $B$,
$40 (i - i_1) = i_1 \times 360$
$\Rightarrow 40(0.2 - i_1) = 360\,i_1$
$\Rightarrow 8 - 40\,i_1 = 360\,i_1$
$ 8 = 400\,i_1$
$\Rightarrow i_1 = \frac{8}{400} = 0.02 \,A$