Question

To verify Ohm's law, a student connects the voltmeter across the battery as, shown in the figure. The measured voltage is plotted as a function of the current, and the following graph is obtained:
If $V_0$ is almost zero, identify the correct statement:

• A. The value of the resistance $R$ is $1.5 \,\Omega$
• B. The emf of the battery is $1.5\, V$ and the value of $R$ is $1.5 \, \Omega$
• C. The emf of the battery is $1.5\, V$ and its internal resistance is $1.5$ $\Omega$
• D. The potential difference across the battery is $1.5\, V$ when it sends a current of $1000\, mA$

Answer 1

Answer: (C)

$V = E - Ir$
when $V = V_0 = 0 \; \Rightarrow \; 0 = E - Ir$
$\therefore \; E = r$
when $I = 0, V = E = 1.5 \,V$
$\therefore r = 1.5 \, \Omega$.