A battery with an open circuit voltage of 10 V is connected to a load resistor of 485 Ω and the voltage measured across the battery terminals using an ideal voltmeter is 9.7 V. The internal resistance of the battery is closest to

Correct option is B

Given:

• Open circuit voltage of the battery = 10 V,
• Load resistance = 485 Ω,
• Voltage measured across the battery terminals = 9.7 V,
• Find the internal resistance of the battery.

Solution:

1. Calculate the current through the circuit:
   The current (I) flowing through the circuit is given by Ohm's Law:
   Current (I) = Voltage across the load (V) / Load resistance (R).

   Substituting the values:
   I = 9.7 / 485 = 0.02 A (approximately).

2. Determine the voltage drop due to the internal resistance:
   The voltage drop across the internal resistance is the difference between the open circuit voltage (E) and the terminal voltage (V):
   Voltage drop = E - V = 10 - 9.7 = 0.3 V.

3. Calculate the internal resistance (r):
   Using Ohm's Law for the internal resistance:
   Internal resistance (r) = Voltage drop / Current.

   Substituting the values:
   r = 0.3 / 0.02 = 15 Ω.

Conclusion:
The internal resistance of the battery is (b) 15 Ω.