Question

In the circuit diagram find:

(A) Equivalent resistance
(B) Current shown by the ammeter A

Answer 1

Given: a circuit with three resistor in combination of parallel and series, a $4V$ battery and an ammeter, A.

To find (A) equivalent resistance, (B) current shown by the ammeter A

Solution:

Let, $R_1=5\Omega ,R_2=3\Omega ,R_3=2\Omega ,V=4V$

And let the total current flowing in the circuit be $I$

From the circuit, it is clear that $R_2$ and $R_3$ are in series,

Therefore, $R_s=R_2+R_3=3+2=5\Omega$

And this series combination is in parallel with $R_1$,,

Therefore, the equivalent resistance of the circuit is,

$R_{eq}=\frac{R_1\times R_s}{R_1+R_s}⟹R_{eq}=\frac{5\times 5}{5+5}⟹R_{eq}=\frac{25}{10}=2.5\Omega$

Now Net current in the circuit is, $I=\frac{V}{R}=\frac{4}{2.5}=1.6A$

So the ammeter reading is $1.6A$