Question

In the given circuit the ammeter reading is zero. what is the value of resistance 'R' -

• A. $100\Omega$
• B. $10\Omega$
• C. $0.1\Omega$
• D. None of these

Answer 1

The correct option is A $100\Omega$

Let, i is the current flowing through the circuit. In the given circuit the ammeter reading is zero.
Hence, the voltage drop across $500\Omega$ resistance is 10V (as the batteries are oppositely connected).
The current through $500\Omega$ resistance is,
$i=\frac{10}{500}$
$i=\frac{1}{50}A$
Hence by Ohm's law for resistance R, we can write
$R\times \frac{1}{50}=2$
$\therefore R=100\Omega$