Terminal potential difference accounts for internal resistance drop

Steps:

• Use formula for terminal pd: V = ε - Ir, where ε is emf, I is current, r is internal resistance.
• Calculate internal voltage drop: Ir = 160 A × 0.05 Ω = 8 V.
• Subtract drop from emf: V = 12 V - 8 V = 4 V.
• This gives the voltage across the battery terminals.

Why B is correct:

• Terminal pd equals emf minus Ir per the definition of internal resistance in a circuit.

Why the others are wrong:

• A: 0 V implies total emf loss internally, but Ir is only 8 V.
• C: 8 V is the internal drop Ir, not the terminal pd.
• D: 12 V is the open-circuit emf, ignoring the current and resistance.

Final answer: B