Question

Seven identical lamps of resistance 220 $\Omega$ each are connected to a 220 V line as shown in figure. Then the reading in the ammeter will be

• A. $\frac{1}{10}$ A
• B. $\frac{2}{5}$ A
• C. $\frac{3}{10}$ A
• D. none of these

Answer 1

The correct option is D none of these

Given : $V_{AB}=220$ volts $r=220\Omega$

Equivalent resistance between A and B $R_{AB}=\frac{r}{5}=\frac{220}{5}=44\Omega$

Thus current flowing through ammeter $I=\frac{V_{AB}}{R_{AB}}=\frac{220}{44}=5$ A