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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 V0 is almost zero, identify the correct statement:

The emf of the battery is 1.5V and the value of R is 1.5Ω

The potential difference across the battery is 1.5V when it sends a current of 1000mA.

The value of the resistance R is 1.5Ω

The emf of the battery is 1.5V and its internal resistance is 1.5Ω

Solution:

Correct option is D. The emf of the battery is 1.5V and its internal resistance is 1.5Ω
V = E − Ir
when V = V0 = 0 ⇒ 0 = E − Ir
∴ E = Ir
When I = 0, V = E = 1.5V
∴ r = 1.5Ω