Question

Four identical resistors of $\,4 \Omega$ each are joined in circuit as shown in figure. The cell $B$ has emf $2\, V$ and its internal resistance is negligible. The ammeter reading is

• A. $\frac{3}{8} A$
• B. $2 A$
• C. $\frac{1}{2}$ A
• D. $\frac{1}{8} A$

Answer 1

Answer: (A)

Here three resistances of $4\, \Omega$ each are connected in parallel so that their combined resistance $=\frac{4}{3} \Omega$.
It is in series with ammeter, battery and last $4\, \Omega$ resistance.
$\therefore $ Net resistance $R=\frac{4}{3}+4=\frac{16}{3} \Omega$
$\therefore $ Current in main circuit $=$ ammeter reading,
$i=\frac{E}{R}=\frac{2 V}{\frac{16}{3} \Omega}=\frac{3}{8} A$