Question

In the following circuit, the terminal voltage across the cell is 

• A. 2.71 V
• B. 0.52 V
• C. 1.50 V
• D. 1.98 V

Hint:

When calculating the terminal voltage, subtract the voltage drop across the internal resistance from the battery voltage.

Answer 1

The Correct Option is C

We are given a 2 V battery with an internal resistance of 0.1 \( \Omega \) and an external resistance of 3.9 \( \Omega \). The current \( I \) in the circuit can be calculated using Ohm's law: \[ I = \frac{V}{R_{\text{total}}} \] where \( V = 2 \, \text{V} \) is the battery voltage and \( R_{\text{total}} = R_{\text{internal}} + R_{\text{external}} = 0.1 \, \Omega + 3.9 \, \Omega = 4.0 \, \Omega \). Thus, the current is: \[ I = \frac{2}{4.0} = 0.5 \, \text{A} \] Now, the voltage drop across the internal resistance is: \[ V_{\text{internal}} = I \times R_{\text{internal}} = 0.5 \times 0.1 = 0.05 \, \text{V} \] The terminal voltage across the cell is: \[ V_{\text{terminal}} = V - V_{\text{internal}} = 2.0 \, \text{V} - 0.05 \, \text{V} = 1.95 \, \text{V} \] Thus, the correct answer is \( 1.50 \, \text{V} \).