Batteries store chemical energy, measured in joules

Steps:

• Identify what a battery does: converts stored chemical potential into electrical energy.
• Recall that electrical devices use current (flow of charge), voltage (potential difference), and power (rate of energy transfer), but storage is the energy itself.
• Note battery capacity is often in ampere-hours, but fundamentally, it holds energy equivalent to charge times voltage.
• Confirm unit: energy is in joules (J), as work done by electric fields.

Why B is correct:

• Batteries store chemical energy, released as electrical energy; the unit joule (J) measures energy per the definition of work in physics.

Why the others are wrong:

• A: Current (A) is the rate of charge flow, not what's stored—batteries provide it, but don't store it.
• C: Same as A; current isn't stored.
• D: Energy per second (J/s) is power (watts), the rate of energy delivery, not stored energy.

Final answer: B